height / normal discrepancy

I have encountered a problem - when I have multiple different texel densities on UV islands, Painter incorrectly renders normals.

This is a test mesh in Blender - the rectangle has denser UV [2.5x to be exact]:

Here we have incorrect normals in Painter with a visible rectangle:

But when tessellation is on, height displacement is calculated and rendered correctly:

All mesh maps are baked.

It seems to me that the quantity of decreased normal is directly proportional to the ratio between the two texel densities.

This is a substantial problem since height in Painter is ubiquitous.