First, yes - I have disabled ALL addons. Using stock Blizzard UI, I can’t pick locks on my rogue. When I click the spell (in the spell book or on the action bar), it immediately casts. You can no longer click the spell and then target the item to unlock… Which means you can’t unlock anything.
Anyone else having this issue or am I crazy?
Ok, after re-enabling all my addons, it works again. WTF?! That makes zero sense but whatever.
So, yeah. Never mind.
The world of addons is murky and complicated. Just disabling them doesn’t really get rid of them - they are still there, just not supposed to be doing anything. To test fully clean you need to temporarily rename your WTF folder so it doesn’t load cached stuff out of there trying to be smart.
Turning them off and on again did probably bump some dark corner of one of the addons you’re using to check itself and stop messing up your Pick skill so I guess all good now.
I have the same issue, i tried turning off all addons and back on and so forth, it’s still a cast for me 
Have the exact same issue on my rogue. Pick lock just casts immediately without being able to select what to pick.
same issue here too. Was able to pick locks a couple days ago, and now it just wants to cast without a target.
This isn’t an addon problem. I renamed the holy trinity and still the skill just casts without allowing a target.
It seems to work somewhat randomly, with or without addons.
As Solitha concluded, it seems entirely random. Sometimes it works, but most of the time it doesn’t. I just submitted a ticket on it, but won’t be surprised if I get the canned “fully disable all AddOns” response as opposed to an actual fix.
I’ve had this problem, but only when I take a lockbox out of the guild bank and try to pick it right away. If I turn around so my back is to the bank, it works fine. Which leads to wonder if it’s one of the many weirdnesses of the interact key.
I have this problem if I’m too close to a mailbox. Step away a few yards and it works properly.
Worked like a charm. Awesome post.Binjali.
Thank you Teerza and Binjali! Now I can finally open all these dratted boxes.
Confirming it has everything to do with the Interact option. Turning that off allows normal usage of Pick Lock. So does moving away from interactable objects.
So let’s revise the bug: Pick Lock should not work as a weird alternative Interact key.
Thanks! Moving away from the mailbox fixed it for me as well.
Thank you, ran into this, issue still happening today 
Thank you, Binjali! It still happens
This also worked for me. Thanks!
Thaannk Yoouu!!! Worked for me.
Happened to me today as well, moved away from the mailbox and suddenly I could use pick lock with a target again. Hopefully this is fixed soon going on 6 months now. 0 addons fresh install.
Nice to know this hasn’t been addressed in nearly a year.
As of August I’m still having this problem, and as of August this still resolved it. Thanks so much Binjali!