Can I get some more help with this? I thought I had it all figured out, but apparently I don't (although the logging advice was very useful).
When I configure my app to consume an api method (see screenshot below), and click test, the correct response is received.

However, if instead of passing 12345, I pass TestVar, where TestVar is a variable of type text, and is set to "12345", the request returns with no information and the error log in service studio gives the following error:
Could not assign 'System.Byte[]' to 'tblName.ROW_VERSION'... Unable to cast object of type 'System.Byte[]' to type 'System.IConvertible'.
The service is querying a sql server database, and tblName.ROW_VERSION is a timestamp field in a table the service is querying. I don't understand why this error is being thrown. Can anyone help me gain some insight into what is going on?