Time Machine does not automatically create local snapshots

[lliu_mds]

Hi guys, long time lurker here. Just received my new MBP several days ago, and have been trying (unsuccessfully) to have Time Machine create local snapshots without an external SSD so that things don't get lost before I get my hands on these. Any help is much appreciated!

Problem:

Time Machine does not automatically create local snapshots despite "Backup up automatically" being checked. No periodic backups are seen in Time Machine itself or in Disk Utility "show[ing] APFS snapshots".

Things I've tried:

1. in Time Machine preference, turn on "Back up automatically", which obvious didn't work because an external disk is required (per Apple's official doc).
2. in console:
   1. tmutil enable to turn on automatic backup. This seems to have worked since the "Back up automatically" box was checked in the preference GUI after running the command (reference).
   2. tmutil localsnapshot to create a couple of ad hoc snapshots. This also worked as evidenced by output of tmutil listlocalsnapshots /.

System specs just in case:

1. Monterey 12.0.1 (21A559)
2. M1 Max MBP, 10 CPU, 32 GPU, 64GB RAM, 1TB storage

Disclaimer:

1. System disk space is nowhere near full