Adobe Animate Project Won't Export to Encoder

I have made a small animation to use as the outro to my YouTube videos on my channel, but i can no longer export it.

I use a MacBook Pro with Adobe Animate 2020. My typical export process is File - Export - Export Video/Media. Then i set the format to H.264 with preset Default (AME) and hit export. At which point Media Encoder automatically opens, and my video file is created. I have made multiple animations this way.

I had been doing this with no issues on the current project i'm referring to. Yesterday evening and this morning i exported it this way a few times just to check the animation was okay, as playback on my application is slow. However, this afternoon after animating a drawing of a character raising their arm, covering 5 frames, i can no longer export. When i click export, the box appears showing 'Exporting SWF Movie' and the bar reaches 100%, Media encoder opens, and then that's it. Nothing else happens, and my animation doesn't export. I have tried to export again multiple times with no luck, even trying to just export 1 frame and nothing is working.

I went back to an animation project i made last month to see if that would export. It's made up of hundereds of frames, music, sound and the final video lasts 3 mins, and that still exports no problem. But the 15 second basic animation i am now trying to export won't export at all.

I've seen a few people post about this and i can't seem to find any clear answers. I don't really want to have to export it to PNG or using other software, as there's never been a problem with the eway i export before. If anyone can help me out i'd be extremely grateful, this is driving me mad!