Safari won't show non-app store extensions

Dear Apple Developers,
I tried to open a Safari Extension I coded in Xcode.
I checked "Allow Unsigned Extensions" in the Safari Develop menu.
When I try to run the App it shoots out this: 'Optional(Error Domain=SFErrorDomain Code=1 "(null)")' what should indicate that either my bundle id is wrong or that it's correct but not mine. I checked and it's correct.
I'm pretty new to this all so I don't really have a plan on how to fix this myself. I also tried different signing methods from none to personal team and from sign to run locally to development - that doesn't seem to have an impact.
What I'm noticing though, is, that every extension I downloaded from the App Store works and shows up very well.
So what is going on?
Thanks in advance :)

PS: Also, I had this error a while ago and it resolved itself after several restarts. But that's pretty annoying.

If you run into this issue again, please collect a sysdiagnose and file a feedback report at https://feedbackassistant.apple.com

Safari won't show non-app store extensions
 
 
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