I have tried something some time ago.
I turned collision check ON and created regions:
So then you can not import all real collision regions to the next operation.
Only that red which were found.
Behavior in any release.
If I draft that wall 1deg, region was found + as a collision region:
Then when do import collision regions, this region is imported as well.
So PR was made PR9383635 because work as designed (no collision region for open areas) was not an answer to me for this particullar case.