When I save a project and then open it, some polygon settings have checkboxes that shouldn’t be there (which I did not put), such as “Enable vegetation mask override” along with the “Exclude” option below. In my case this issue affects polygons that are configured to exclude only all buildings.
In other words, every time I go into my project, I check every polygon and make sure the settings are set correctly, because the system might have saved the polygon settings incorrectly.
Hi,
We have reproduced your issue and found a possible fix for it. Thanks for noticing the problem 
Regards,
Xavier / Asobo
I noticed the same problem, would be glad if it would be solved soon!
Thank you!
Same issue here. Any estimate of when this will be fixed?
Will the fix be available in SU5 Beta? The more polygons I add to the scene, the more polygons are affected by this problem, it becomes very difficult to work. And also the problem when vectorsplacements are not saved in groups is annoying.