I don't know if this is a custom UI problem, or whether this is happening with the default UI as well. What I do know is that this is happening with both Copper Enhanced and Lucis Interface, and it's annoying as hell.
The lengths for hotbars aren't always saving properly. Sometimes they do, and sometimes they don't. What this means is, every third or fourth time I log in I'll find many of my hotbars are now the default length of ten slots.
As they say, a picture is worth a thousand words:
edit: I'm not going to be logging in much until this is fixed. Having to spend half an hour fixing all your hotbars every second or third time you log in, is for the birds...
The lengths for hotbars aren't always saving properly. Sometimes they do, and sometimes they don't. What this means is, every third or fourth time I log in I'll find many of my hotbars are now the default length of ten slots.
As they say, a picture is worth a thousand words:

edit: I'm not going to be logging in much until this is fixed. Having to spend half an hour fixing all your hotbars every second or third time you log in, is for the birds...