Hi Mark,
One possibility that comes to mind is that the UIOnly model may not have its row & value ready for the Account model condition to use. Try to make sure the Account model is loading after the UIOnly model. Maybe as a test, you can add a button to your page, and only query the account model via the button. If it works after page load is complete, then I think this timing might be the issue.
Also, make sure the two fields are both the same type - basically, datetime and date fields are not equivalent.
