My best guess for what's going on is that some of those values were zero but got saved with something like 6e-13 (i.e. "approximately zero") or smth. (maybe two different near-zero values?)
IIRC, I've had a similar issue with near-zero values before.
Costume files can be viewed with a text editor to check.
If so, it might be worth checking:
* read other saved costume files in your text editor and compare the slider values
* Try (making a backup of the costume file and then) deleting the slider values from the costume file and seeing what happens when you load it