When you go to edit an off duty costume/outfit, the Tailor UI is automatically set to Uniform. This causes the tailor to strip down your outfit to the starter uniform layout, removing all of your selections and customization. Unless you have previously saved an appearance, you will lose it and have to start from scratch.
Not game breaking, but a bit tedious especially with regard to color selection. Would it be possible for the creation of an off duty or formal outfit to 'lock' the tailor into that costume type when selecting the modify drop down slot?
Even before F2P, this 'feature' was being criticized.
I'm sure it's quite hard or tedious (or most likely, tons of other stuff to do) to code it so the game will 'know' what category costume the captain/boff is wearing and behave accordingly. The game doesn't even know if I'm conning a starship or joyriding in a shuttle. But they did give us 'Load Costume Only'..
At least you know the work-around for it. I'd keep backups of the 'saves'. If you'd like, you can rename the files (just make sure the name starts the same way as the original files, i.e. "costume_" ) so you know what is what.