Ok, I investigated this a bit.
The only way I can replicate error is: Drop the model on platform, do NOT rotate it! Apply uniform scale 1.02. Slice the model with shell thickness 0.8.
Anything else, rotating the part aroud z-axis, thicker shell, or another scale, then the part is filled correctly. So it must be something in the math of infill.
Fix horrible type A does not remove error.