Garmin Varia Radar RTL515 - no Connection possible

I can't connect my Garmin Varia radar to the locus Map 4 app. The message always appears: No device found.
I've already put the Varia into pairing mode, reinstalled Locus Map, turned Bluetooth on and off several times, etc..

I use an Android smartphone and the Varia is found very quickly there and the radar is also found quickly in the Garmin Varai app.

Could someone help me to find out why it can't be found in the Locus Map app?