Looking to see if anyone else has come into this issue
I cannot for the life of me figure out what addon or addon combo is doing this.
When i move something from bags > reagent bank or normal bank or banks > bags it will auto close both every single time.
As you can imagine beyond frusturating
The best way to figure out what addon is doing something weird is to turn off half you addons. If that fixes it, then turn off half the remaining addons. Repeat until you’ve isolated the addon causing issues. This isn’t perfect, as sometimes problems are from two addons interacting with each other, but it’s a good first place to start.
Just had to do a Google search and found your post as I’m having this same issue. Noticed it last night on my main, but it quickly went away by itself after a reload or something, but now I’m playing on an alt and it’s happening again. I’d imagine it’s something to do with ElvUI. Do you use that as well?
But yeah, they’re closing after every action. Equipping, vendoring, moving, etc.
Went into ElvUI and just checked and unchecked the same boxes in the ‘Bags’ tab, and then reloaded and it went away btw. If it happens again, I’ll just try a simple reload by itself and see if that fixes the issue, but it appears to just be a bug with ElvUI atm.
This is happening to me as well. I even tried toggling the bags off/on in the Bags tab but it didn’t work for me.
If you have been updating ElvUI rather than deleting it and replacing it, you need to delete and replace it. They made some significant structural changes to the way the addon’s modules are stored and a whole new folder is in play.
There is overlap between things in that folder and things in the original implementation that will cause mystery errors.
This won’t affect your settings. Don’t touch the WTF stuff. Just delete ElvUI and ElvUI_Options and reinstall the addon from Tuk or WowUP or whereever.
I did replace it by deleting the old folders first, then copying in the new folders.
Perfect. They’ve been warning folks of that since I think the .03 version. But if you haven’t been on the discord, you might not have known. 
Even with the 13.07 update it’s still happening.
I’m not seeing any difficulty with ElvUI.
Have you gone through their debug routine?
Their discord has details on that.
I had this same issue, but only for one of my characters. The other 6 characters were fine.
For me it wasn’t ElvUi, instead it was AdiBags that I had to reset to default in the options to correct it.
The bag toggle/reload in ElvUI worked for me.
Using newest Version of Elvui and this was only happening on one Alt. As described, went into Elvui options for bags and disabled and reloaded. Re-emabled and problem has disappeared. I had major issues when DF was first released but re-installing as mentioned above made all those issues disappear.