Android Smart Phone App requires restart to establish connection

Most of the time my NUKI Android app can not establish a connection to the bridge when started for the first time, no matter how long I wait. If I force-close and then restart the app it’s usually working immediately.
It happens with different Android devices, so it does not seem to be realted to the device. I have a Samsung Galaxy S10 with Nuki App v2.9.0 installed.