For the past several days I have been unable to shift-click item stacks in my bags to split them or to shift click items at vendors to buy more than one. Similarly I am unable to ctrl+click equipment to view the appearance on my character. This is affecting all characters on retail WoW, but not in Dragonflight beta.
I have disabled all add-ons, reset my key bindings, deleted all WTF Interface and Cache folders, and even uninstalled all versions of the game completely. Nothing seems to resolve this issue.
I submitted an in-game ticket and Blizzard linked me to wowhead and the forums and marked it resolved. There does not appear to be a way to re-open the ticket on the website or in game. I have heard that the state of support for the game was dire, but the inability to even re-open the ticket after someone pasted a response without reading and closed it is really something else.
I am out of ideas on what could be causing this and have exhausted my options.
My post in the UI and Macro forum: Cannot split stacks of items