Motion Studio stores your license key and other preferences in a configuration folder.
Some of these files might have gotten corrupted in an update to Motion, or from Adobe which could cause Motion to work incorrectly.
This issue usually presents as a random, repeatable, "crash" of the extension window, or a "blank" window when you attempt to open the extension
Configuration location
By removing the configuration folder, you will get a 100% clean installation. Please note you will also lose things like saved palettes, easing curves, and tool defaults. If you would like to keep these, create a backup of the respective files in the motion-studio-stable/db/... folder.
You may have to "Show Hidden Items" to see this folder on Windows.