During the break I’ve switched over to nonseasonal hard-core gameplay, and although I have been completing Bounties, the plans for the level 70 versions of the Captain Crimson and Cain sets refuse to drop.
Any ideas how I can force the issue?
In the past I have been able to get uncooperative plans to drop by doing public Bounties, but do you know if that will work in this case?
You might want to try vaults, especially an ancient one, as there is a goblin that drops plans also so that might give you a better chance.
Still, afaik plans will drop until you get them all so it’s only a question of time even if stick to keep doing bounties.
Pure RNG as far as I’m aware. No trick to force it.
Maybe a sacrifice to RNGeezus?
I had a similar issue. Found all three of the updated plans for NS/SC pretty quickly, but it took (iirc) 30-40 acts worth of bounties (as in 6-8 full sets) to find them in NS/HC. They did eventually drop.
All I can confirm 100% is, I have seen a ton of complaints about it. Haven’t seen a blue post saying if the drop rate is intentional or not.
I think your just having bad luck lol. It will eventually drop for you, just gatta keep GRINDING!
The same way as you got them in SC mode when you asked at the release of the patch
Simplest Way to get plans besides bounties is to farm for rainbow goblins, not that you find them but all the likely spots in Area 1, 2, 3, 4, 5 where gobs appear can be checked out for such as for the Odious Collector which besides dropping crafting materials also offers a high chance of dropping crafting recipes that are still missing in your collection. Of course you find the same from Bandit Shrines. 
Just do bounties.
The wife missed the plan the entire season 18 aswell. So we did three full bounty runs during this weekend, and then it dropped.
The last plans is a little bugged in dropping, but it will drop. And the bounty mats is not wasted anyways, compared to doing goblin runs, which will take time but yield nothing to your endgame.
There are certain places among those suggested spots that offer 2 gobs on the same level in one location and like 3 you can dash to quickly after doing bounties that drop something most of the time. So yeah its worth 3 or 4 mins if you are hunting for crafting recipes such as blacksmith or gem recipes for the season journey requirement.
I don’t suggest all the places only some of the places (not to waste time)
hint only do first three in area 1 as a suggestion.
Very helpful replies, guys. Except for Steve, who remains salty and unhelpful to the last…
I didn’t think of the Vault, and that’s something I will try first tomorrow.
I got my UE up to 90, but 95 scares me with that build.* So I wanted to try the Crimson rebuild, and I was irked to see that I have neither of those plans on this account.
I’ll give it a shot tomorrow. Bedtime now. Thanks again! 
*I sure wish the damn leaderboard would track best times per set.
I’m honestly surprised that you didn’t get them on the season 18 side. That should have brought them over to the non-seasonal side after the merge at the end of the season.
Had problems finding the new plan i non season (didn’t play season 18). I saw a tip about doing some bounties on one hero and opening them on another (maybe even a fresh hero?), so I did some bounties and opened the caches on another hero and I finally got the plan. It was probably just a coincidence, because isn’t the content fixed already when the cache drops? So it’s not a Stone-proof method!
Killing monsters should do it
Blacksmith Plans and Jeweler Designs only drop from Bounty Cache and Odious Collectors. So, “killing monsters” won’t do, unless they’re part of a Bounty or the “monster” is an Odious Collector Goblin. 
Blizzard was suppose to fix it so Bounty Caches would guarantee Plan and Design drops until they were all collected. But, some just refused to drop. That’s one of the reasons the Blacksmith now automatically learns the Sage’s Journey Set as soon as you Train him to Level 12. 
Some people have said that creating a new character and getting them to 70 and then farming some bounties and killing green gobs sometimes helps a stubborn plan to drop.
Try with different characters. I got Captain Crimson on one of the characters. I didn’t get the new Aughild untill I did bounties on another character… or it could be just RNG.
Well, this was my sixth trip to Guardian for the Season, and I was short of time because of (cue nausea) life obligations, so when I could play I went as fast as I could and only got to Destroyer, so I shorted myself my 13th stash tab as well.
I’m going to dump a bunch of my guys into one game and do a “public” Bounty, and see what turns up.
That’s what I’ve done. Twice now prior to registering my complaint.
Yes, it is. They fixed that back in the early days (it’s been so long I’m starting to get confused about the time frame of vanilla, early ROS, patched ROS, etc.), when players would obtain Bounty Caches on Normal, and then take them to T10 to open them, get rewards from that level of difficulty.
Bounty Caches are now linked to the difficulty level in which they were earned, and taking them to any other difficulty or opening them with any other character won’t change the contents.
Update: Tried it with 2 other players in the game. No joy. Also each of the other players had both of the plans already.
Personally, I believe that most things other players try is just coincidental and the Plans just drop when they want to drop.
Still, try this, if you haven’t already: If you have a Rank 25+ Gem of Ease and some Puzzle Rings stashed, create a new Level 1 Character. (Even if you delete it later). Put the Gem of Ease in the most powerful Weapon you have. (Assuming you have one stashed). Run The Vault on Hard or even Master Difficulty. Don’t worry about leveling your Character to 70, although you’ll probably level up fast anyway. If one of the Goblins there doesn’t drop the Plan(s) try a round of Bounties. (A “round” being 5 Bounties in all 5 Acts).
If you still don’t get them, then you’re at the mercy of D3 RNG.
Well, I did 2 rounds of this guy’s route, found a truckload of goblins (no Rainbow), an Odious Collector, and a Vault, but no plans…
Will go at it again tomorrow…
No real trick. The drop rate from odious collector goblins and bounties is RNG and way less than 100%.
Just keep doing split bounty farms. I got mine this past week from a T10, T16 (crimson), and T13 (cains) and I ran 30+ split farms before seeing all 3.
I had success opening the bounty caches on a fresh 70 (not the toon that did the bounties).
I hear that has worked for others as well.