I’ve noticed the latest version of the app, 1.2.2 seems to have more issues in this area than the previous version did. Perhaps it was automatically updated by your phone?
Often the problem is not actually the connection but the app’s display. Assuming you have an iPhone, check Settings | Accessibility | Hearing Devices to see if the phone is actually connected to both aids.
If the aids are connected in Settings, usually things get cleared by just tapping one of the icons on the bottom (‘Sound’ or ‘Hearing Aids’) and back.
Sometimes turning off Bluetooth and/or the aids is required. But that is rare for me.