Enabled DLP policies don't seem to be doing anything in OneDrive

I'm trying to get DLP to identify very obvious social security numbers, credit card numbers, routing numbers, and passport numbers.

I've enabled DLP in two tenants (one production, one test; they're not connected in any way) and scoped the applicability to certain OneDrive accounts. I'm using the default HIPAA, US PII, and US PCI templates, but making them so only one value will cue the policy to take effect (I'm not touching the matching % because based on their definitions, my test data [which is real information, just used for test purposes] are clearly within the matching bounds).

At first, I tried just a US PCI policy with all OneDrive accounts (not SPO, not Exchange) in the test tenant, and it did fine finding the file with the credit card number and routing number.

Then I tried to apply the rest of the policies only to my OneDrive account (which, oddly, you have to enter using the OneDrive's address; you can't search for a user). No luck.

In the production tenant, I've got scoped policies set up with the same test data. No luck.

I've tried switching between test mode and on mode (the former removes any sharing barriers and only shows the warning icons on files; the latter closes down sharing, as I had set it up). No luck.

Reindexing the OneDrive account doesn't work (nor should I have to do that for all of my accounts once it's enabled globally anyway).

It's not acknowledging anything at all. Any issues anyone is aware of with DLP and implementing it correctly? I'm at a loss and don't know who to reach out to at this point.

It should just work.