I cannot reproduce this bug in FileMaker 12.02 in Windows XP.
Both <> and ≠ resulted in correctly filtering the portal.
We use FileMaker in a FileMaker Network sharing environment.
Users with 12.01 get correctly filtered results, users with 12.02 experience the <> and ≠ issue.
After upgrading the host to 12.02 the <> and ≠ operators are working again.