H.264 export glitches [Title edited by moderator for clarity]

Hi, I'm a beginner using AME, but basically I exported a composition from After Effects to Media Encoder in a H.264 format (so it can be opened by QuickTime) and after I render it and open the video it has some glitches it looks like some frames are slower than the original ones so it makes the video look like it's in slow motion. I've already tried the different renderer options, different presets, the frame rate is compatible, etc.. I have no clue what more I can do to find a solution. It happens with all the compositions I made in After Effects.