Comment 4 for bug 1719474

This is not a graphics/display issue but rather caused by repeated and synchronous database access while selecting multiple playlists in a row:

https://www.reddit.com/r/DJs/comments/8cku9r/mixxx_21_released_with_revamped_skins_and_effects/dxg7unh/

Finally I got it ;)

We should try find a workaround at least for 2.2. and maybe also for 2.1.x. This will affect all users that use the encoder for scrolling through the left pane! I usually grab the mouse for this purpose and only noticed it recently while updating my mapping.