I cannot fix this because Apple will not tell me what is the problem even after I run their verification tests that pass. You need to work around the problem. After you try to and it says this, you need to
- Go to Systems Settings > Privacy & Security
- Scroll down near the bottom to the Security section
- Click Open Anyway next to Shotcut
- Then, it gives you another warning dialog. Click Open Anyway
- Finally, it asks for your password or touch ID.