I had this problem before. It just stop rendering at a specific timing. I’m not sure if you had the same problem but let me tell you mine.
I don’t use video footage, all files are created in photoshop and illustrator. Due to my little knowledge, i imported a .psd file which is so huge that after I placed on the composition it is way out, I did nothing and just shrink it. Turns out the rendering will just stop at certain timing.
Solution: I did a mask over my the .psd file and solve the problem