I can no longer access SMB shares from Ubuntu after updating to DSM 7.2-64570 U1 (DS1621+)

This morning I updated my DS1621+ from DSM 7.1.1-42962 U6 to DSM 7.2-64570 U1. After the update I am no longer able to access shared folders from my Ubuntu machine. All errors in terminal and Portainer indicate "access denied", though no passwords have changed, and I am still able to access the shared folders from Windows. I am mounting shared folders with SMB but also tried NFS when SMB stopped working, as that appears to potentially be easier to manage (no usernames/passwords?).

Any help or direction to a fix is greatly appreciated.

EDIT: Realized I had a typo in my mount command for mounting an NFS share - I was using ip.address:/shared_folder instead of ip.addres:/volume_name/shared_folder. Fixed that and now have no problems using NFS to mount the shared folders to the same mount point as before, so for me that's a suitable workaround and presumably a better solution than SMB anyway, since both client and server are Linux OSes anyway.