When going to windward close-hauled, you wouldn't necessarily want nor expect your top tell-tail on the main to flow all the time. As a rule
of thumb, try to get the top tell-tale to flick between flowing out straight and folding back behind the main so that it is flowing about half of the time and folding about half of the time.
The above advice is generic and results may vary for a given boat, wind
shape, tell-tail position relative tot he top of the sail, etc. I merely wish to point out that when close hauled you don't necessarily want / need your top tell-tail to flow all the time.
If in doubt, talk to your sail maker.