Hello Karl!
I took a quick review of the bug in question, [BUG-000108852 - Definition query validation incorrectly states no records were returned]. The instructions of the bug mention a dataset that we don't have in Support. Development likely had it when they addressed the issue, or were able to reproduce the issue with another dataset. However, I'm having trouble reproducing this with my own dataset.
Do you have a dataset you can reproduce the issue on, and are you able to provide it? If not, I can keep fiddling around to see if I can pin this down, though getting a dataset directly from you may be quicker.
Let me know! We're happy to investigate as long as we can reproduce the issue for you!
Best regards,
Rachel
Esri Support Services
Rachel Guttmacher
ArcGIS Online Technology Lead
Esri Support Services