Customers disappearing from Sage 100c

We are running Sage 100C, 2016 Premium.   We have just noticed that customers are disappearing from Sage 100.  Their customer numbers are gone in Sage 100, but we can still see the customer number in Sage CRM.   We aren't sure exactly when this started to happen as we have a large (19K record) customer base.....but the 6 that we know of were on a June 25 spreadsheet.

We need to figure out what happened so we can try and back into how many are gone.

We have logging turned off because it makes the system too slow. 

Anyone know of a SQL query to try and figure out what happened?  

Thank you!

Ann