Youth email message in SB+ but not SB

I have a Scout (134400730) who has a scoutbook/my.scouting.org account and shows up to email within SB+, but does not show up to email within regular Scoutbook. I prefer to use regular Scoutbook for the moment since we’ve experienced so many problems with SB+ email and I am looking for something reliable. Is there a way to figure out why this scout does not appear in SB for messages? Our registrar says he shows with an account and the same email for both and she doesn’t know why he doesn’t show in SB messages.

Thanks,
Megan

@MeganPirchner SB Legacy relies on the user login in at least once for messages - so I assume that user has never logged into Legacy SB>