If you are getting a black screen when clicking Quick Photo or Adding a Photo to an Activity, you likely have turned off access to the camera for the Theia Health app. Based on your phone type, follow the instructions below.
iOS
Open Settings
Scroll down until you start seeing all the apps installed on your phone.
Find "Theia Health" and tap on it
Toggle on "Camera" if it is not already on
Android
Open Settings
Tap Apps
Select the "Theia Health" app
Tap Permissions
Tap Camera
Choose Allow only while using the app or All the time