It’s a very annoying bug! It shows that the developer needs to be verified first so you can install or use the apps. But verification is only needed for Enterprise Certificates. You are using a Personal Developer Account, You don’t need to verify!

Here’s the fix!

1. Go to “Settings > Privacy & Security”

2. Scroll Down to Developer Mode and turn it off

3. Restart the device

4. Open the sideloaded app or reinstall the sideloaded app and then it will tell you to Enable Developer Mode again.

5. Turn it on and you are good to go!

Disclaimer: You may need to try multiple times for it to work!