SMB shares pointing to password-encrypted datasets are not visible for use by Time Machine after they are unlocked until SMB is manually restarted.
Steps to reproduce:
1. Set up a password encrypted dataset
2. Create a Time Machine share on the encrypted dataset
3. Reboot TrueNAS
4. Unlock the dataset
5. On a Mac, notice the share isn't visible to Time Machine, and that TrueNAS doesn't advertise _smb._tcp over mDNS
6. Stop and start the SMB service on TrueNAS
7. On a Mac, notice that the share is now visible to Time Machine, and that TrueNAS advertises _smb._tcp over mDNS
With legacy GELI encryption, unlocking a pool would restart services including SMB automatically. Perhaps something like that isn't happening with the new native encryption implementation.
The attached debug is from a test VM I set up just to make sure I could reproduce this issue.