Transactions disappearing

I have struck an unusual problem with Home & Business 2020 recently.  I reconcile my credit card accounts every month and they have always balanced in the past.  Over the last couple of months, 2 of my accounts didn't balance and put the missing balance in Find with no results which obviously meant it was not from one transaction. I went back through my transactions and eventually found them all, one going back 2 years.  They must have been entered because when I put the payee in, it came up with the exact transaction in the search box, but it came up with no record in any accounts.  These transcactions were from more than one payee and I have done nothing to make them suddenly disappear.