Media encoder fails to render a Character animator scene

Hi all,

I have created a puppet with Illustrator and then I have introduced it into a scene with Character animator (30 seconds). No problems at all with this part.

Now, I want to export the result into a mp4 video but the Media Encoder does not finish the process never ever (2,5 hours of "codification process" without a "remaining time" estimation (blank) I think is "a little too long" for a 30 seconds video)

I am using the latest versions of both programs and yesterday I was able to export 2 different scenes (one with the same puppet/character and another with a different one) without problems, but now seems that the Media Encoder did not work properly at all...