Can't Create Folders in Guild Stash + Lost Guild Stash Tab

Went into my Guild Stash and was attempting to create a folder with a standard tab selected (not a currency tab/affinity-based tab/quad tab). When I clicked the 'create folder' button, the tab simply disappeared, no folder appeared, and the 'create folder' button is now greyed out.
It would've been where '6' should be in the list.

Upon relaunching the game this morning, the problem has resolved itself.