OK - I am having the same issue.  I just upgraded to 2020 this weekend.

I tried to apply your fix.  The terms SHOULD be credit card - but even with today's date, it is showing past due.  So I changed the terms. starting with net 10 and working up.  I have found that if I change the terms at least 4 times, the system will get rid of the Past Due.   While this is a solution it is not really workable - I have 20 invoices showing past due, even if they are on Net 30 or 45 days.

Looking for a solution that doesn't take so much time perhaps?  Because this is an ugly bug to deal with on an ongoing basis.  Thanks!