Operating system: Windows 10 (Home)
Graphics card: Nvidia 1070
Broken: 2.90.0 (Steam)
Worked: Not sure, Has been like this since before 2.79b
When the default select mode is changed from Left to Right Mouse button Lasso Select no longer works with Tweak + RMB Any.
Splash Screen Change on initial set up or Select button or Edit - Preferences - KeyMap - Select With Mouse Button
Affected: any View Mode that has the Lasso option. (Edit mode, Object Mode, Grease Pencil, etc)
Exact steps for others to reproduce the error
See attached MP4.
Based on the default startup or an attached .blend file (as simple as possible).
Start Blender and use Start up Cube.
Temporary fix if the Select key is changed from Left to Right Mouse Button is to walk through the KeyBindings and set anything that uses Lasso to Tweak Right and anything that was using Tweak Left to Tweak Right where Lasso is was changed.