There is one tip in your description, it happens on the top surfaces.
Some clears are worse than others, but when piled on they get "milky" turning a whitish look. And even if they don't turn white, as time goes by they die back because of all the solvent that is trapped there.
You don't get it on the sides because you aren't applying it as wet and if you did it would likely run all over the floor. But because they are horizontal surfaces you could pour it out of the can and it wouldn't run. So because of this you are applying it super wet.
One of the dead givaways in trouble shooting is admiting what YOU did different where the problem occured.