gpsmap 64st bluetooth connectivity

Just received a 64st and have connected to my Android phone using Connect app.   Have a problem and one basic question.

Question: When I power on the 64 it connects to my phone even if the app is not running.  Is the app supposed to be running for notifications to show on the 64?   I closed the app at one point and notifications continued to show on the 64.

Problem:  Even with the app still active in background, the 64 disconnects after a while, even with the phone in close proximity.  I press the power button and the Bluetooth indicator is flashing instead of solid.  I don't think the phone is at fault because it has no problem maintaining bluetooth connection with multiple other devices I own.