Therm Warning - max no. of meshing

[Dominik K.]

Good Afternoon,

THERM version 7.8.71 07/10/23

In the file attached, I had a warning:

if I click OK, there are results:

% of error is very high. 

I checked the setup and preferences, and it looks all right. No hanging, no further errors. On a very similar detail of the window sill, there is no issue. Already tried various Quad Mesh setups with no success. 

What could be a possible issue?

Thanks

Dominik