So having upgraded to 10.13 beta 1 (10.13 Beta (17A264c)) I'm seeing invalid snapshot errors during fsck / boot
Booting single user results in fsck barfing with error 8 and a message about in invalid unecrypted file
Recovery mode does something similar
Running Disk Repair results in this
Verifying file system.
Volume could not be unmounted.
Using live mode.
Performing fsck_apfs -n -l -x /dev/rdisk1s1
Checking volume.
Checking the container superblock.
Checking the EFI jumpstart record.
Checking the space manager.
Checking the object map.
Checking the APFS volume superblock.
Checking the object map.
Checking the fsroot tree.
Checking the snapshot metadata tree.
Checking the extent ref tree.
Checking the snapshots.
Snapshot is invalid.
The volume /dev/rdisk1s1 could not be verified completely.
File system check exit code is 0.
Restoring the original state found as mounted.
Operation successful.
This is a 10.12 upgraded to 10.13 iBin (Late 2013) Mac Pro