I dont know if this has been reported already but.... Whenever i use a summoning sack i glitch and cant click on anything, i try to move my window up and down to unglitch myself but i end up having to cc to fix it.
I've experienced this as well as the inability to use skills can still regular attack but can't use any abilities.
Sounds silly... But try using a potion when this happens. I've noticed when I've become "skill locked" using a potion has "unlocked" me. (I do not mean skill lock from monster effect, also called seal. I mean the bug where no skills work but you can move around freely). However I've also noticed the clicking issue frequently in Fm while browsing too.
this happened to me the other day with a summon sack. moving it to a diff spot in my inventory fixed it. also what sila said.