Message not being received by app until phone is restarted

Hardware setup:
I have two phones, each paired to their own T-Beam and running 1.2.17

Behavior:
-Phone A can reliable send messages to Phone B where they are received.
-Phone A cannot reliably receive messages from Phone B once some period of time elapses (it works for a short while, and then stops working).

Investigations:

-After a while, if I examine the list of nodes on Phone A, I can see that it appears to have stopped getting any updates from either it’s own node, or the one on Phone B (the ‘last seen’ counter keeps going up as if it has lost contact with the nodes). In spite of this, I can still successfully send messages from Phone A to Phone B and they are received.

-Restarting Phone A solves the issue for a time, but it returns eventually.

-I do not believe the issue lies with Phone B, or it’s hardware, because I have tested with two different boards on Phone B and have the same issue. Also, the issue is fixed temporarily by re-starting Phone A.

-This behavior persists well past the sleep windows of the hardware devices. I let it count up to an hour and a half on the ‘last seen’ counter and the behavior persisted.

-Phone A shows only 1 out of 2 nodes active in the notification tray when this behavior is present.

Unpair the phones, pair phone-A to TBeam-B and phone-B to TBeam-A.

That will at least tell you if it’s the phone or the node.

Good suggestion - I have done this, but to no avail. Seeing the same behavior.

Update: After I waited around for about 90 minutes, a message did finally get through from Phone B to Phone A. I had the SENDNG node wired up to my COM port so I could capture some debugging info: this is what the log looked like around the time the message finally went through:

https://pastebin.com/339jgZfw