In 2.55 Builds 50 and newer, there is an issue with a combo editor shortcut.
Normally, pressing Shift Control + or - lets you shift the base tile used by a group of selected combos.
In these newer Builds, this appears to work normally at first. However, refreshing the combo editor (closing and opening it) reveals that any animated combos have reverted to whatever tiles they originally used. If you perform the mass shift, and copy those shifted combos, the copies also reveal the animated combos did not shift.
If something changed with the tile or combo data post build 48, then this shortcut needs to be updated to work correctly.