I have not been able to reproduce this issue so far.
I can no longer recreate this issue when turning debug off.
It is possible that I added the -l switch to the alias definition - the filter alias has to be globally visible for debug to be able to call it.
(This is not a bug, but it would be nice if "debug @debug filterident" is called from within a script for "alias -l filterident { stuff }" within the same script to work.)
