Get fails for table with RecordID as primary key

We have discovered a bug in NAV 4.2 or lower which is causing us serious problems. If you have a table that has 1 primary key of type RecordID and you add record ids that are numerical and also alpha numerical, then when you use the GET C/SIDE function it fails when you go from get for a numerical only ID to the alpha numerical ID in a loop. Any example of the data is below and is based on Customer table in the demo database of the NAV product.

I have a table with only one field of type RecordID. I take recordIDs for the Customer records in the record table and add them into my table. I then call GET(recorded) to retrieve an earlier stored record.

IF I only add record IDs where the key is numbers only its fine
RecordID GET result
Customer: 12344 OK
Customer: 12345 OK

IF I only add record IDs where the key is numbers and letters its fine
RecordID GET result
Customer: AB123 OK
Customer: IC123 OK

However, If I add a mixture it fails on the first call to the change in type as I loop through calling GET.
RecordID GET result
Customer: 12344 OK
Customer: IC123 FAIL

It is very easy to reproduce this using a simple table and report based on the customer table which adds records in the OnPreReport and GET in the OnAfterGetRecord. Running the report for all customers in the sample database causes the crash. I can email a .fob of this test to anyone who would like a look.

Anyone any ideas?