Hi,
I faced the same problem as you last time. It really get me crazy.
What other UT member recommend me to do is, DON'T use

DO FORM myform TO myvar.
Instead,

DO FORM myform
lc = myform.property
myform.release

for this, you should hide your form instead of release if user click on OK/CANCEL button.

I follow it, and the problem never occur since that.

HTH