Keyframes won't work

one thing you can try and do is nest it. It worked for me and saved me a mental break down.

I tried some methods that were told here and they didn't help me, but I found my way. The rendering of a given area helped me.
1. Put the keyframes you need.
2. Select the moment where the keyframes do not work and use the "I" and "O" to set the entry and exit points.
3. Go to Sequence -> Render Selection
After that the change can be seen

I've been trying to find the solution to this same issue and nothing here has worked but I did a fix.  The opacity change using keyframes stops working when I have another "Effect" added to the clip.  I have a "Levels" effect added to the clip that's not working. If I remove the Levels effect, the opacity keyframes work. When I add it back again, the the opacity change stops working again.  Hope this helps someone.

Okay, so nesting the clip worked for me but was a terrible solution for what I had been working on. Putting the keyframes on the nested sequence was a pain in the a** because of the croping it makes. 

I found a different solution. Turns out this issue happened because I had a retime on that clip (I dind't notice this before because I didn't have a retime, but a reverse time effect). So, the easiest thing to do would be to delete te retime, put the keyframes, nest the clip and then do the retime on the nested sequence.

Voila

The only solution that worked for me was "nesting the clip"...that works fine now

Try it! Hope it helps

I was literally ready to cry, break my machine and then cry A LOT MORE!  For some reason, this worked--but this is not what I normally do for keyframes.  THANK YOU ALL!!

This just deleted all my projects. I saved my project before doing this and I'm very disappointed it was my very first project I worked on for 7+ hours just gone. Anyway I can get it back?

I was going crazy too, and then I realized the problem went away when I shut off the paintbox effect I had on to create a border.

Although this post was dated almost three years prior, the fix worked for me!  Spent two hours trying to keyframe a picture and was getting SOOO frustrated.  Found this community and Voila.  Now, hope it stays fixed.  That would be Premiere Pro 2020.

I have tried every "fix" in this thread and every other place. Nothing works. Keyframing an image in a video to have it scale down, then slide across the screen. I set the first keyframe at 100% size, x and y coordinates, and change those numbers for my end keyframes and a few in between. It moves and resizes the picture just fine while setting the keyframes, but when I play it back in the preview, the picture just sits there at its original size.

Yes, I have trashed prefs.

Yes, I have cleared the cache.

Yes, I have tried to nest it.

Yes, I have restarted the program.

Yes, I have rebooted my PC.

Yes, I have plenty of hardware to run this program.

Yes, I have done literally everything the Adobe support community keeps suggesting over and over.

ZERO RESULTS. None. Nada. Zip. Zilch. Squat.

This is a pretty serious bug for a program that is used for keyframing like 90% of the time.