So, I don't know if I am alone on this one. but even as a guild master, I sometimes encounter guild bank bug where I can't take out or even move things in a single tab. I have unlimited "limit" on everything and I can put one thing in the bank and suddenly I can't take anything out or move things around. Sure, simply closing and opening the gbank SOMETIMES help or I have to relog, but it is still a bug. Maybe it has something to do with certain addons?
No, this has been a bug since forever. When you move much stuff around the entire guild bank stops working for like 10 seconds. You don't have to close the guild bank; all you can do is wait.
I wonder how hard would it be to fix this. But I guess this is not really a top priority for Warmane, same as trinkets procing when you fly and change zones.