BPM Null rule not working as expected

Within our requisition BPM workflow (ReqApproval), I am trying to create a rule that rejects a requisition when they do not add a Project. I was able to isolate for a specific projectID and the test results were successful. I then changed the rule to 'is null' or 'isn't null', rejections don't occur at all, all reqs approved. I have included an attachment the screenshots of the rules and am wondering if anyone knows how I can reject reqs when projects are null.

Version: 21B