Can't Modify Webi Schedule Prompts

BI Launch Pad 4.1 SP3

While attempting to schedule a Webi, I discovered that I could not actually modify the 'Prompts' section. The button is there: the window pops up asking for the prompts, but if I attempt to apply the prompts, it just takes me back to the pop up window with the old/default values still in there.

Schedule permissions for the Webi app, report, etc., have already been applied.

Thanks,

David