Steps to repro:

1. open new project
2. add Probuilder package, open Probuilder window
4. add new cube to scene
5. select "face" tool
6. observe faces can be selected, highlight when mouse hovers over
7. in inspector, reset script component "Pro Builder Mesh"
8. observe faces cannot be selected or highlighted

Note: reopening project does not fix the issue

Reproduces: 2020.1.0a9 (Probuilder 4.1.0), 2019.2.2f1 (Probuilder 4.0.5), 2018.4.7f1 LTS (Probuilder 4.1.0)