The "most popular" function on the OPAC does not honour the opac suppression in the 942$n subfield.
I think this is because "most popular" is based on a database query, and the opac suppression is in a MARC field which is indexed in Zebra.
I think the solution is probably to create a biblio.suppressed field and have the 942$n store data in that field. Then we check that database field for things like "most popular" and other database queries.
*** This bug has been marked as a duplicate of bug 19704 ***