Enable Jetifier Popup fails to render properly

### Please fill in the following fields:
Unity editor version: 2018.4.23f1
External Dependency Manager version: 1.2.155
Source you installed EDM (from .unitypackage or Unity Package Manager): PackageManager
Features in External Dependency Manager in use (Android Resolver, iOS Resolver, VersionHandler, etc.): All
Plugins SDK in use (Firebase, Admob, Facebook, etc.): FireBase, AdMob, Facebook, HelpShift, IronSource
Platform you are using the Unity editor on (Mac, Windows, or Linux): Windows
Platform you are targeting (iOS, Android, and/or desktop): Android
Scripting Runtime (Mono, and/or IL2CPP): IL2CPP

### Please describe the issue here:
After Upgrading to 1.2.155 from 1.2.151:
- Editor receives a Android SDK not found while at the same time a popup trying to prompt "Enable Jetifier" appears.
- Enable Jetifier does not have anything rendered beyond the Title of the box.
- You are unable to interact with the button, leaving the editor "frozen"

### Please answer the following, if applicable:
What's the issue repro rate? (eg 100%, 1/5 etc)
100% on machines that get the issue.
Was able to get it reproed on a previously working computer by clearing the entire repo Library folders and importing the whole project from the beginning.