GPS issues on Rak2287

Issue: Getting constant stream of “$GPGSA,A,1,99.99,99.99,99.99*30” and similar data from GPS, unable to actually acquire time/location.

Setup: Rak2287 and Pi Hat on Raspberry Pi 4 (4GB Mem version). Running both Rak firmware and Default raspberry pi OS (with compiled drivers from Rak download).

Server: TTN and Chirpstack

Details: I am seeing the same issue described in this thread (RAK2245 TTN-Gateway: no GPS?), except that I have the Rak2287 card. Otherwise, the symptoms are identical. I have confirmed that the Pi can communicate to the GPS chip over ttyAMA0, and am getting similar data stream described by hdtodd:

(from cat /dev/ttyAMA0):
$GNVTG,N2E
$GNGGA,0,00,99.99,56
$GNGSA,A,1,99.99,99.99,99.99
2E
$GNGSA,A,1,99.99,99.99,99.99
2E
$GPGSV,1,1,01,24,117E
$GLGSV,1,1,00
65
$GNGLL,V,N7A
�b 0x������$GNRMC,V,N
4D
$GNVTG,N2E
$GNGGA,0,00,99.99,56
$GNGSA,A,1,99.99,99.99,99.99
2E
$GNGSA,A,1,99.99,99.99,99.99
2E
$GPGSV,1,1,01,24,127D
$GLGSV,1,1,00
65
$GNGLL,V,N7A
�b ??x�����$GNRMC,V,N
4D
$GNVTG,N2E
$GNGGA,0,00,99.99,56
$GNGSA,A,1,99.99,99.99,99.99
2E
$GNGSA,A,1,99.99,99.99,99.99
2E
$GPGSV,1,1,01,24,117E
$GLGSV,1,1,00
65
^CNGLL,V,N*7A

I’ve disconnected/reconnected the GPS antenna, and confirmed the upx connector on the card is OK.