Lesson challenges suddenly stopped working


Changing the animation type worked for me. Thanks, Tirao 

Tirao wrote:

from Chess.com Support, workaround worked for me:


I'm really sorry about the issue with lessons' challenges! Our developers are currently working on fixing that bug. The workaround is to change your pieces animation type to "Medium (default)" in Pieces and Board settings here: https://www.chess.com/settings/board

This worked for me.  Thank you, Tirao and OwnerOfHell!