Now before someone says this, I know, don't AMA link H.264 footage. This is not part of the workflow, just something that I ended up with that didn't work and I'm curious why it has not worked.
I had some After Effects projects near completion that I left render overnight to reviews. Since it was overnight anyway I had them rendered as H.264 though Media Encoder with the HD 1080i 29.97 preset. After having issues with other players I tried to AMA link the files in Avid to look at them that way (which I was certainly able to do after importing the files), but the AMA link had only the audio and the first frame of the video. Regardless of the playhead's position or whatever part of the clip was placed into the timeline, it would only display the starting frame of the media.
I have AMA linked H.264 media before. It is usually a little slow and not great for non-rendered play, but it has still linked appropriately. At this point it is just curiosity, but I am wondering if someone knows what might have caused this issue.