ORA-12713 character data loss in NCHAR/CHAR conversion

Hello,

We recently migrated from Wintel 2008 R2/Oracle Forms 11gR2 to Linux RHEL6/Oracle Forms 12c (12.2.1.3.0)

In Linux we are encountering the error: ORA-12713 character data loss in NCHAR/CHAR conversion.

I have isolated the problem to the users entering the section sign (double S) into free form fields.

When queried from the database into a base table field it renders as ?

When the same field is retrieved via a database package procedure into a form field the ORA-12713 error occurs.

If the same DB procedure is executed in SQL*PLUS, the data renders as a small circle with an underscore underneath it. Sorry, I cannot find Unicode character or symbol on-line.