Shotcut won't export as mp4

I have tried for the last month or 2 attempting to make a video into an mp4…each time having it say failed or Shotcut has closed unexpectedly… this has only happened when i added a mp4 or mp3 clip to my video. I have turned off parallel processing and it still hasn’t worked. Does anyone have any suggestions???

I am on a MacOS high sierra

Upgrade to the latest version 18.01. Versions prior to 17.12 had a bug on MP3 with album art that you might be running into. Also, ensure that GPU Processing is turned off in Settings menu.

I am upgraded to 18.01
Is there any other problem that may be the cause of this??
I have turned off GPU…and I’ll attempt to see if this solve the problem. (it didn’t work)