Unable to manually set ActionMutate behavior

In Selection Interface, I'm unable to customize the behavior of ActionMutate in the Mutation menu:

1. Select a residue, press 'M' for Mutation menu.

2. Manually check boxes for ResidueTypes I want to allow.

3. Click on background or 'B' to go back, or 'Y' to start Mutate.

4. Checkboxes reset (!) and Mutate follows default behavior.

Note: Within the Mutation menu, the buttons 'J', 'Z', and 'X' function as expected and effectively toggle "Apolar," "Polar," and "All" ResidueTypes; this successfully changes the behavior of ActionMutate. It seems that only manual adjustments are not registered.