Looks like I found the solution. This is so dumb and I don't know what had happened to cause it.
Since Alias 2021 was working just fine, I thought maybe the UserPreference of Alias 2020 must be messed up somehow, so I went to -
C:\Users\<username>\AppData\Roaming\Autodesk\Alias\UserPrefs2019\Preference Sets (Windows 7 and Win10)
/Users/<username>/Library/Preferences/Autodesk/Alias/UserPrefs2019/Preference Sets (Mac).
Those paths basically, and just erased the UserPrefs of the corresponding version and then started the application. And this time the application asked me if I wanted to use default preference since it could not find any at its target folder and I said YES PLEASE. And Viola! Problemo solvedo.