[6.10.0-rc5] ACLs in /mnt/user not working

After upgrading from 6.9.2 to 6.10.0-rc5 all ACLs in /mnt/user stopped working. Hower ACLs on the disks (/mnt/disk[1-6], /mnt/cache) itself are working fine. Disks and Cache are formatted with btrfs (encrypted).

Example:

g0dscookie@nas:/$ ls /mnt/user/isos
ls: cannot open directory '/mnt/user/isos': Permission denied

g0dscookie@nas:/$ ls /mnt/disk5/isos
Windows  proxmox-ve_7.1-2.iso

g0dscookie@nas:/$ getfacl /mnt/user/isos
getfacl: Removing leading '/' from absolute path names
# file: mnt/user/isos
# owner: administrator
# group: domain\040admins
user::rwx
user:administrator:rwx
group::rwx
group:domain\040admins:rwx
group:isos\040ro:r-x
group:isos\040rw:rwx
mask::rwx
other::---
default:user::rwx
default:user:administrator:rwx
default:group::---
default:group:domain\040admins:rwx
default:group:isos\040ro:r-x
default:group:isos\040rw:rwx
default:mask::rwx
default:other::---

g0dscookie@nas:/$ getfacl /mnt/disk5/isos
getfacl: Removing leading '/' from absolute path names
# file: mnt/disk5/isos
# owner: administrator
# group: domain\040admins
user::rwx
user:administrator:rwx
group::rwx
group:domain\040admins:rwx
group:isos\040ro:r-x
group:isos\040rw:rwx
mask::rwx
other::---
default:user::rwx
default:user:administrator:rwx
default:group::---
default:group:domain\040admins:rwx
default:group:isos\040ro:r-x
default:group:isos\040rw:rwx
default:mask::rwx
default:other::---

g0dscookie@nas:/$ id
uid=1461716048(g0dscookie) gid=1461715457(domain users) groups=1461715457(domain users),1461716076(isos rw),[...]

I've already rejoined samba to my Active Directory and reapplied ACLs. /mnt/user seems to be able to read/write ACLs, however it doesn't seem to actually apply them.

If I chown the directory to g0dscookie I can access it through /mnt/user/isos. Same with chgrp to "domain users".