Hello guōriōur,
Thanks for posting on Apple Support Communities. I understand that you would like to allow camera access to several third party apps on your iPhone. At this time you are unable to do so. If you launch the Camera app does it function properly? Are you able to take photos? If so then the issue may be with some settings.
Start by checking the Camera settings. You can do so by tapping Settings> Privacy> Camera> Enable any app that has requested access. If you don't see the app that was originally requesting access on that list you will need to check the settings for that particular app. Make sure to allow camera access in the settings of the app.
If the settings are correct, try the following troubleshooting steps next, testing after each:
- Restart your iPhone.
- Check that you have enough available space on your iPhone. How to check the storage on your iPhone, iPad, and iPod touch
- Verify the OS is up to date. Update your iPhone, iPad, or iPod touch.
- Remove the app and then reinstall it.
If the issue continues you may need to contact the app developer directly. How to contact an app developer.
And you can contact Apple Support for possible diagnostics.
Cheers!