Animation work Film Ceases to Play at End of last Animation Point

[Ezad]

Hello
I don't want to lose what I have developed working with Animation, Toggle Key Frame.
The film is MP4. It is slightly over one hour. I got to around 8 minutes 50 seconds - and then the movie fails to advance by frame / or to play. It holds one frame as though the rest of the film were one photo. The film play fine out of AE and it played all the way through in AE when I started the project. I attach a clip to show how the film behaves where I left left off with Toggle Key Frame.
Let me know what is the solution to getting the film to play, to advance frame by frame so I can continue work on the project.
Thanks!

[Warren Heaton · Accepted solution]

You'll want to get familiar with Keyframe Interpolation.

Animation > Toggle Hold Keyframe tells After Effects to switch between a type of Temporal Keyframe Interpolation that allows change over time (Linear, Bezier, Continuous Bezier, or Auto-Besier) to one that does not allow change over time (Hold).

From what you have described, it sounds like you are working with Time Remapping and that you inadvertantly set a "Hold" keyframe.  Locate any keyframes that are square in shape, select them, and choose Animation > Toggle Hold Keyframe to change it back something that can change over time.

[Ezad]

The work on the timeline -as I advance I manage to collect a few frames that need to be animated. Thus I end up with those keyframes that are square in shape. Those square shaped keyframes are stationed in multiplicty from the start of the film to the point as showing in the video. If I were to choose (select) all those square shaped keyframes and 'animate' they would revert back the film as it was before the work on animation. Isn't there an obvious indicator that would show me which keyfram(s) are on hold? 

Thanks!!

[Ezad]

Ok

What I did was to remove the last animnated keyframes on the time line and the video did play. 

As indicated must have accidentally create a hold on a keyframe. 

Thanks for answering this thread.