That sounds like the units need to work with council to get the registration worked out. One of the pack Key 3 might be able to pull up the scout’s BSA ID using the non-renewed member report in my.scouting. I’ve never tried it, so I’m not sure what’s included in the report.
ETA: Looks like @edavignon suggested this (and gave directions how) in another similar-ish thread: Scout with new account - #18 by edavignon