I ran into an issue with the latest version of Vuforia with a HoloLens/Spatial Anchor application that I've been working on. With the previous version (7.1.35), everything worked great. The primary functionality of the app was to use spatial anchors to reset my content so when the HoloLens looses tracking (i.e., "Mapping surroundings"), the location of the content would be restored when tracking reinitialized. I forced this by covering the sensors with my hands and running around like an idiot, then would uncover the sensors and after a few moments the content would restore itself based on the spatial anchors.
With the new version of Vuforia, when I cover the HoloLens sensors and force a "remapping" the app essentially freezes and never recovers. At this point I'm pretty sure I have Vuforia disabled in my app (i.e., I'm not actively tracking any markers/targets); however, I'm pretty sure the issue is tied to the newest version of Vuforia.
To test, I reverted back to 7.1.35 and ran the above described test. Everything behaves as I expected it to. I then upgraded to 7.2.20 again, and performed the same test with the same negative results. Hopefully this is the right place to post this type of content, if not please point me to the appropriate location.
EDIT - I am using Unity 2018.1.1f1