Namespace doesn't match file system. Expected 'null'

I am using Consulo for working on a Mono project (and added GTK sharp NuGet package to make GTK apps). I am using .net 4.7.2 with C# 8.0
I get this warning
Namespace doesn't match file system. Expected 'null'
This warning shows up in every c# file, even if the namespace matches the file system!
I believe this warning should not be present at all. It is ok if namespace doesn't match file system.
If it's match file system - can you show example? Directory and file paths. Also you can disable it inspection (three dots)
About this null - looks like i fixed that today.
You can test in nightly channel(https://github.com/consulo/EntryPoint/blob/master/Update%20Channels.md) - but need be careful.