Yes, it's a very annoying limitation.
There is a workaround though. In the import steps set it up statically as if it's going to import from a known file path so you can specify the worksheet. Then add a secondary import file path that's your variable.
As long as the first statically named file doesn't exist on the machine the import step will fall through to the variable path while retaining the named worksheet preference.
Hope that helps!
Perren, that worked! Thank you so much!
FileMaker, this needs fixing!
regards - paul
Oh, that is SO cool, Perren. I hope they don't 'break' this in the next rev and/or FIX it permanently so that we CAN specify worksheet in a parameter that can be used by the variable path method.