Tools Rel 9.1.5 - Can't clear grid cell error after returning from custom visual assist

Hello,

I have a custom headerless detail form and one of the grid columns has a custom visual assist associated with it. The visual assist is called from "Visual Assist Button Clicked" event.

If the user first enters an incorrect value an error is set on the grid cell through event rules (Set Grid Cell Error). When the user then uses the visual assist and returns, event rules validates the value returned and then does a (Clear Grid Cell Error) however the error is NOT getting cleared on the form.

I have stepped through using the debugger to confirm that the Clear Grid Cell Error is getting called.