GPS Rescue disarms immediately upon reaching fixed altitude during descent phase (DVR video included)

Describe the bug

During GPS Rescue in Fixed Altitude mode (set to 130m), GPS Rescue was triggered at 330m. The quad successfully turned around, returned towards home, and began descending. However, the exact moment the quad reached the 130m altitude threshold, the flight controller unexpectedly disarmed all motors mid-air, causing a free fall and fall off the ground. (sanity checks off). Crash video (rescue start at 5:50) https://www.youtube.com/watch?v=PWV646GF_N8

To Reproduce

1. Configure GPS Rescue with gps_rescue_alt_mode = FIXED and set return altitude to 130m.
2. Fly the quad to a higher altitude (e.g., 330m) at some distance from home.
3. Trigger GPS Rescue (failsafe/switch).
4. Quad climbs/returns and begins descent towards the fixed altitude.
5. As soon as the altitude telemetry hits 130m, motors disarm instead of leveling off or continuing controlled descent.

Expected behavior

The quad should level off at the configured fixed return altitude (130m) and continue cruising toward home, or transition smoothly into the controlled descent/landing phase without triggering an unexpected disarm or false sanity check.

Support ID

0bd58cb4-2e20-4efb-ba04-3395f7af7bfe

Flight controller

GEPRC TAKER F405 BLS 60A V2 STACK

Other components

VTX: DJI O4 Pro GPS: TBS M10Q GPS Receiver: ReadytoSky Nano RX 2.4G ELRS Battery: 4S 21700 4000 mAh li-on Motors: Emax Rs2205

How are the different components wired up (including port information)

• GPS connected to UART (TX/RX + 5V/GND) with Compass enabled via I2C (SCL/SDA).
• DJI O4 Pro connected to dedicated HD VTX UART.
• ELRS Receiver connected to CRSF UART.
• ESC connected via 8-pin harness with DSHOT protocol.

Add any other context about the problem that you think might be relevant here

Attached is the complete Blackbox log (.bbl) file covering the flight from 330m to the unexpected disarm event at 130m. Attached is the full .bbl file. The relevant flight for this incident is: Log 58/66 (04:35 - 11:44) (total 7:08)

BTFL_BLACKBOX_LOG_20260831_023912_GEPRCF405.zip