thank you for coming back to this issue.
I'm using a 560Ti currently.
It is good to hear, that you can confirm and resolve this bug.

However, as mentioned in the original post, I also had an issue, where my workaround of using a dummy fragment shader first (which should be more or less equal to your workaround) did not solve the issue.
Unfortunately, I'm too busy atm to test fully test it again.