Subject "DROP CONSTRAINT" only shows effect after commit?

any attempt to do a search ends with the screen

Polls feature not enabled

for some reason, so I have to ask directly:

Is it correct, that a commit is required after some contraints have been removed, before I can do some data changes which would violate those constraints?

Hoped to do it in one transaction, but I'm getting a violation error for one of the removed contraints when inserting some data, although a check via RDB$RELATION_CONSTRAINTS says the constraint isn't there anymore...

Best regards,