How to set up TrueNAS SMB

[ladal1]

Hi, I'm trying to set-up new SMB share after upgrading to TrueNAS Core 12.0 and I need to set up ACL - The goal is to make the share visible and fully accessible by one user (account on truenas) and invisible to others. However whatever change I make to the ACL doesn't seem to reflect and both Domain and Name in the Edit Share ACL seem to vanish after saving and opening it up again. Currently it seems that every user has read capability but no write and I can't seem to be able to change even that.

EDIT: Figured out part of the problem, but now all my tries to add a user specific permision end on: [EFAULT] SID lookup for truenas\\smbusers\<username> failed: failed to call wbcLookupName: WBC_ERR_DOMAIN_NOT_FOUND Could not lookup name truenas\\smbusers\<username>

Thanks so much for help.