FR935 Blue Triangle Crash with Varia Lights

A Forerunner 935 experiences a device crash to the Garmin blue triangle when a running a CIQ application with an AntPlus.LightNetwork instance that references either a Garmin Varia RTL515 or a Garmin Varia UT800, or both, is deployed in conjunction with an AntPlus.BikeCadence instance.

An ANT+ cadence sensor need not even actually be paired with the FR935 for the crash to occur.
The manufacturer of any actual cadence sensor that may be paired makes no difference.
The order of activating the Varia lights makes no difference.

The FR935 does not crash if the RTL515/UT800 are not paired.
The FR935 does not crash if only the RTL515 is paired only as a Radar sensor.
The FR935 does not crash if no Light Network members are physically switched on.
The FR935 crash can occur, but does not always, upon setting an un-paired UT800 into pairing mode.

The FR935 can crash spontaneously when no CIQ application is running, for example whilst in the Sensor Menu, and even when no CIQ application is installed,
for example upon re-pairing the lights after a master reset of the FR935.

The incidences of crashes is much reduced, but not eliminated, if the Light Network is formed before entering the CIQ application. If the Light Network re-forms, as it does
frequently, whilst the application is running then the FR935 will crash nine times out of ten.

Other ANT+ sensors, with corresponding CIQ AntPlus instances, such as speed or power, do not cause the FR935 to crash when the Light Network is activated with paired lights.
The CIQ application subject to the crash may be an Application or a Widget, it makes no difference.

There is no CIQ error report or log produced by the crash.

The following error log in GARMIN/DEBUG/ERR_LOG.TXT (or .BAK) is produced upon each crash, with the same register and stack values, regardless of which of the lights are
paired/activated, every time :

2691 (Forerunner 935) SW ver: 2100
Build Type: RELEASE
Commit:411945a33c8a05df9cd2f1c12eb8016bcf860647
ESN: 3963023305
07/22/21 17:03:14
RTL
errnum: 0x034
r0: 0x2000bac0
r1: 0x2000b8f8
r2: 0x105d84f9
r3: 0x00000000
r4: 0x16443611
r5: 0x00000005
r6: 0x200578d4
r7: 0x20057734
r8: 0x10422441
r9: 0x2000b8f8
r10: 0x00000005
r11: 0x0017b590
r12: 0x20057728
r13: 0x000c4eb9
r14: 0x2000b8e8
r15: 0x105d976b
r16: 0x16443610
r17: 0x410f0000
r18: 0x40000000
r19: 0x00000100
r20: 0xe000ed38
r21: 0xe000ed34
r22: 0x00000000
Stack frame PC, SP: 0x000c1999, 0x2000b828
Call Stack - SP at 0x2000b828:
0x00086937
0x000abc89
0x10422441
0x000021c5
0x105d84f9
0x10422441
0x000c4eb9
0x105d976b
0x105d976b
0x105d84f9
0x0000c001
0x000abac7
0x000baeb3
0x00041ff9
0x000a4351
0x1042b703
0x1059ce0f
0x000430ab
0x000a4345
0x000a2fdf
0x000a2be9
0x000a472d
0x00044b61
0x00044ef7
0x00045c4f
0x000a24e5
0x00000000
0x00000000
0x00000000
0x00000000
0x00000000
0x00000000
Uptime: 489771

The Forerunner 935 details are :

SW: 21.00 (411945a)
GPS: 2.70
Wi-Fi: 2.40
CIQ: 3.1.8
BLE/ANT/SNS: 6.90
WHR: 20.03.31

The RTL515 details are:

Model #: 3592
Man. #: Garmin
SW Ver.: 3.32

The UT800 details are:

Model #: 2567
Man. #: 1
SW Ver.: 2.40

CIQ SDK is 3.2.5, Eclipse IDE is June 2021, with the CIQ plugin at 4.0.4.