Vuforia and App freezing, model parts disappearing and then app crashes.

The title explains most of what I'm dealing with. I'm running my app on an Android phone having installed from unity. Sometimes, after scanning an image tracker and the relevant model spawns, vuforia and the app freeze, all UI elements disappear, and then parts of the model start to disappear before the app crashes completely. This doesn't happen every time I use the app but enough that it will be a problem on launch. I'm using extended tracking so the user can move around the model after they scan the tracker. I have a feeling it's related to when tracking is lost but I don't know where to start with catching and preventing a crash like this. I'm using Unity 2020.1.10f1 and Vuforia 9.8.5. I'd really appreciate any help anyone can offer