When properties dropdown options are changed under the "XR Direct Interactor" in the "Prefab Resource" window then the Override window turns to black also while changing properties causes Override window to flicker, refer attached video.

Steps to repro:
1. Create a new project
2. Edit > Project Settings > Package Manager > Enable Preview Package
3. Window > Package Manager > XR Interaction Tool > Install
4. Hierarchy > Create > XR > Ray Interactor
5. Make a Prefab of Ray Interactor
6. Hierarchy > Ray Interactor > Inspector > Overrides > XR Ray Interactor
7. Expand Sound, Haptic, and Interactor Events dropdown under Override
8. Change the properties under Prefab Resource
9. Change the Interaction Layer Mask to Nothing

Actual Result:
Override window turns black and flickers when properties of "XR Ray Interactor" are changed under "Prefab Resource"

Expected Result:
Properties don't change under "Prefab Resource"

Note: XR Interaction Tool is introduced in 2019.3.0a1 with package version 0.0.6-preview

Reproducible in:
2020.2.0a17, 2020.2.0b15, 2019.3.15f1, 2019.3.0a1

Package found version: 0.9.4-preview, 0.9.2-preview, 0.0.6-preview

Environment:
Occurring on Windows 10 & Mac 10.15.