I had originally thought it was a bug introduced by JCE's hack (my bad), but it's actually a clear oversight by the guys who made the changes.
After Hide and Show are used, a bank command slot seems to be "selectable" and it causes the character (in this case, Edward) to be "stuck" if that blank command is selected.
This is an issue with the battle menu code when coming out of hiding, where it isn't updated to allow for only 4 commands (or whatever commands that are listed) to be selectable.
FF2US:

FF4ET:

This affects both versions of FF2US and FF4ET.