Adobe Animate not exporting all frames.

Hello Fellow Adobe Animator's! I've been Having a problem with exporting my animations lately...and it's really bugging me. so, i've been working on an animation for something (which isnt really important) for about 2 weeks or so..it's only a 50 second clip..and today i was finally ready to export. my settings in adobe animate were W: 3840 H:2160 span:entire movie format: H.264 preset: YouTube 2160p 4k ultra HD. those are my export settings...and everything looks about right. after i hit export. media encoder opens up (as it usually does) .I simply export my animation into a folder called "animations" then once im done. i go to my animations folder on my pc to check my mp4 out. and once i watch a few seconds of it.. i notice a few frames are missing. it was bascially like if the a  certain part of the video was cut out on its own. i go back to adobe animate see if i accidentally deleted the frames.. but, no. their still there. so, i export again. and once its back in media encoder (again) i look at exporting setting (in media encoder) to make sure..and in media encoder the preview doesnt show the five frames thats on the actual animation in adobe animate just like how the mp4 was missing those frames. so.. i have been trying to fix this all day..and i cant find a solution. can anyone help?