Progressive CPU Lighmapper 2019.2 - having artifacts on directional lightmap

I started noticing artifacts on the direcitonal map that negatively affect my visuals.

In particular it is visible when directionality "overflows" on adjactent faces, e.g. here:



(left: shaded, mid: lightbake, right: directionality).

This is a 90 degree simple corner, but the directionality on the right side is somehow seeping in from the left side. You can see that the lightbake itself is ok, it's just the directionality that messes up the result.

It's quite independent of the object too - even symmetric objects have the issue happen in random places e.g. the two pillars below are the same prefab moved by 4 metres on X exactly, but the overflow is on different parts:



Apart from not using directional light, any way how to resolve this?

 

Here's the light configuration. Indirect denoiser has been disabled since it causes artifacts of its own.


The baked light is provided by a set of area lights with HRD baked emission:

 

I can confirm that replacing area lights with point lights resolved the issue, so it is most likely the area lights that are problematic.

Any chance the issue could be resolved in a foreseeable future?