I tried Windows 10 and the same problem is present there. So I searched a bit and...
Nexus devices with Android 6 Marshmallow can no longer be connected
I added Flatten to my local store and it seems to work well. Thanks.
In that case it might be a good idea to mention it in the man page.
[Gmail]/Foo mailboxes broken in 1.1.0
For some reason the "Fixed In:" field can't be left empty.
Cannot override mailbox in channel 'gmail' - no Patterns.