Please try to locate the record into the customer and as well into the supplier
If you cannot find it in there please look after retired accounts for both customer and supplier by doing the following:
Log into Safe Financials and select the relevant company.
Click Purchase/Sales Ledger.
Click Suppliers/Customers.
Click Filter and click the Supplier/Customer tab.
Change the Ignore Retired Accounts option to No
If this doesn't work you should look into trading partners.
If you can locate that record into trading partners you should do the following :
Go to Nominal Ledger
Click Trading Partners
Find the Trading Partner
Tag it to be a Customer