Problems with non-existent gaps while Painting

Hello! I’m painting in Toon Boom Animate Pro a hand-drawn animation and I’m having some problems painting due to gaps that doesn’t exist, but Toon Boom sees them. All the lines are closed, there are no visible gaps, I even can’t see gaps in the strokes view, but Toon Boom won’t paint some parts because Toon Boom thinks there’s a gap. I paint with close large gaps enabled and it doesn’t work either. I know it’s a gap problem, because I’ve used the closed gaps tool to try to find the gap that Toon Boom insists that exists. Closing gaps in parts of the image I found out that the “gap” Toon Boom sees is a thick line with no gaps.
The image files are vectorized and in the close gaps property while vectorizing I tried the number 10, 50 and 100 and none of these worked (btw, what does the close gaps option in the vectorization properties does exactly?). Toon Boom doesn’t do this to all drawings, but with some, so I guess I don’t need to say all the other vectorization properties.
I really need some help with this, so I would really appreciate if someone could help me!
Thanks in advance!

Ive just sent the image to your e-mail. I’ve vectorized the image with onepass threshold 50.
Thank you very much for your answer.

I’m guessing you have sorted this. But one trick I have have learnt is to divide up a large area into smaller blocks, then paint them one at a time. You can then identify exactly where the problem is - hopefully!

You could email me a sample file that won’t paint, and I can take a look at it.

I would suggest posting some screenshots of the strokes view here, but it might be easier if I can zoom into the image.