Area Target Test App not working on HoloLens 2

I'm unable to get any Area Target app working on my HoloLens 2, whose system updates are current. I'm using Unity 2021.3.4f1 with Vuforia 10.12.3, and the two Area Targets I've tried are through Matterport using the Pro2 scanner.

When I try to get the Area Targets Test App to work using the guide below, I'm able to build the app, deploy to the HL2, run it initially to create the dataset folders, and then upload my area targets (just the .dat, .xml, and occlusion .3dt files) into the folder using the Device Portal. When I then go to run the app again on the HL2, I do successfully see that the two datasets are registered.

When I go to activate a dataset, however, the loading revolving circle (Loading Scene) does start but then seems to freeze; considering that the animation of this loading circle is supposed to keep going in the Update method, it seems like nothing is happening at all. I've let this go on for 20 minutes and no change to the stuck loading circle, and the dot next to the dataset does not turn green. These scans are not very large (one is <2k sqft, the other maybe closer to 5k). All the other voice commands seem to work. Can somebody please assist with this?

https://library.vuforia.com/develop-area-targets/area-targets-test-app-user-guide