Action blocks disappeared: after duplicating a layer, all the action blocks generated for the previous layers disappeared from the canvas. I tried moving to another page and coming back again with no effect. In the end I exited and reloaded the lesson from the last save and they were there. I attach the log file exported after I reloaded the saved version.

We cannot reproduce this. However, if this happens again, please log a ticket and attach the SB4 along with steps to reproduce the problem, if possible. Thanks!