Help please

[Епр38526468xvpr]

Help me why an invisible key is placed on the mask what to do

[David Arbor]

The keyframe is likely before or after your timeline if you can't see if. If you haven't hidden the column, click the little left or right arrow next to the blue stopwatch icon to navigate to where the keyframe is. Otherwise, you can click the stopwatch to clear all keyframes on that property.