Fade in animation does not render

In an animation im making, i have multiple instances symbols fading in through the alpha color effect in a classic tween. This works fine in the timeline, but once i render it out to an mp4 or test the movie, all of theese effects stop tweening and the symbols just appear without the fade. 

This used to work fine, but after my file got corrupted, and i used the winrar repair technique to get the file back, this issue suddenly appeared. Is there a way i can fix this neatly? Or is my best bet just transferring everything to another project file?