I am missing the recipes for Amethyst, Emerald, and Topaz for the royal gems. I have done many bounties for each zone, Rifts, and Greater Rifts. To the best of my knowledge, bounties is where you get these recipes. If this is were the recipes are suppose to drop, then they are not dropping for me. If they drop somewhere else, please let me know where they drop.
Thanks for your help with this matter.
Unlikely a bug.
Bounty cache and one type of goblin drops plans.
If no more plan (incl. blacksmith plan) drops, that means you had already learned all plans, or you place the plans in stash.
Check you stash carefully, and make sure you choose “Show All” filter on Jeweler’s window.
That would be the Odious Collectors (green Goblins). 
There are some other places that drop plans… I’ve gotten Armory plans from some boss fights. But the gem ones are annoying, you only get one (or very rarely two) and not every cache will have them even if you still need them. To get the last recipe on the PTR I had to run 4 acts getting many blacksmith recipes before I got the last one of the jeweler.
I did a double take and checked my stash - no plans hidden in among the legendary gear and gems. So, no it’s not in my inventory. I have run dozens of bounty runs for each zone and I don’t get plan drops anymore. I have also smashed several goblin fests along with the crafting goblin several times, so if it was going to drop via a goblin it should have done so by now. I think at this point I need someone to slap the side of the loot computer to see it they fall out.
You haven’t mentioned setting the filter to “Show All”. I assume you haven’t.