Folder marked as "unkn" is not synchronizing

Dear Cine,

here we are again, i still have few minor problems with my nokia. We've changed the server and most of the mails that i have, are imported from the old one. So, may this be a problem for the ZxMobile? Some folders aren't showed after a complete sync.
Reading the post Bug 32 – Missing mail folders and bad hierarchy

i did zmmailbox -z -m user@domain gf "/Inbox/Extra" | less
"name": "Extra",
"parentId": "2",
"path": "/Inbox/Extra"

and then zmmailbox -z -m username@domain.tld gaf

7271 unkn 0 0 /Inbox/Extra

suggestions?

Thanks for the support