Custom SoundFonts playing correctly in program but not on website or in exports (MuseScore 3)

(Re-uploading with attachments per Marc's reccomendation.)

I feel like I'm losing my mind. I've gone through this process a hundred times by now and am not doing anything any differently. In the program, I press play and everything is correct. The mixer is correct, I'm exporting the score correct. However, when I upload online or export audio MuseScore is simply not using the custom soundfonts and is instead using incorrect instruments. Does anybody have any ideas? This has never happened before and it is driving me INSANE.

I should also note that when I close or reopen the program only some of the custom soundfonts either a. remain in the library or actually added to the score. I've set these soundfonts as the default numerous times and they just aren't sticking- in order to use them I need to go into my downloads and reinstall them every time. I'm wondering if at this point uninstalling and reinstalling the program in it's entirety would be a good idea.

https://drive.google.com/drive/folders/1LzV2bdIpFLSxwcg-I7HrgYJ3XEOSBk_…

ATTACHMENTS IN THE DRIVE LINK:
- Screen shot of synthesizer and custom soundfonts
- Screenshot of "upload score audio" button checked
- .WAV file of what is being uploaded to the website as well as the audio that occurs when it's exported (whilst correct soundfonts are being played in the program)
- Actual MS score file