Dynamic Expanding/Contrasting Groups of Rows?

So far, this is working pretty well, but I can't get it to not fill in a 0 if the group sheet field is blank.

=LET(v,VSTACK(Group1:Group4!A3:K100000),FILTER(v,INDEX(v,,7)<>0))

If I try this one:

=IFERROR(VSTACK(_xlfn._TRO_TRAILING(Group1!A2:K50),_xlfn._TRO_TRAILING(Group2!A3:K50),_xlfn._TRO_TRAILING(Group3!A3:L50),_xlfn._TRO_TRAILING(Group4!A3:K50)),"-")

I get an Update Values popup browse window looking for a file for each group after I hit enter.