Weird ELRS Issue with Tango 2 + Happymodel Slim Pro TX — TX only works when facing away from drone

[old cape]

Hi everyone,
I'm running into a really strange issue with my ELRS setup and I’m not even sure what to call it.

The setup:

• TX module: Happymodel ES24TX Slim Pro TX (tested on two different units)
• Controller: TBS Tango 2 v3
• Drone: DeepOcean Seeker 3 o4 with ELRS
• ELRS version: All devices flashed to 3.5.3, also tested on 3.5.5
• Regulatory Domain: Tried both 2.4GHz ISM and 2.4GHz LBT
• TX Power tested: 100 / 250 / 500 / 1000mW — makes no difference
• Link to Betaflight dump config: https://pastebin.com/ZSrSWwYL
• Betaflight: RX is properly recognized and mapped but here is my config (dump) -

The issue:
Everything binds correctly using the same binding phrase. Tango 2 connects automatically to the RX.
OSD shows link quality, voltage, etc.

In Betaflight, when I go to the Receiver tab:
AUX channels work fine — I can see switches responding in real time.
But Throttle / Yaw / Roll / Pitch don’t do anything — until I turn my body away from the quad. Then, magically, they start working.

Yes — when I turn my back to the quad, stick input works perfectly.
When I face the quad again — throttle and sticks stop working — AUX is still fine.

It's as if something is interfering with only the stick signal?

What I tried:

• Downgrading ELRS to 3.5.3 from 3.5.5
• Testing both 2.4GHz ISM and 2.4GHz LBT
• Changing TX Power
• Swapping out the TX module (brand new second unit tested) - yes, i bought two modules 🙂
• Updating Tango 2 firmware (was 6.17 → now 6.48)
• Ensuring nothing blocks the antenna — direct line of sight to the quad
• Rebinding multiple times, rechecking channel mapping — all normal

No settings on the RX/TX stand out as incorrect

Any ideas what could be causing this behavior or how I should debug this? It’s honestly driving me nuts.
Thanks a ton 🙏

[frail vine]

Set your TX power to minimum, the Tango cannot provide enough power for higher output. What packet rate are you running? Show a screenshot of the ELRS lua on your radio

[old cape]

@frail vine i have set up 250hz pocket rate, here is my lua config

I set the TX power to 25 mW, but nothing has changed, it still does not work

[frail vine]

Show the ELRS lua with the receiver connected

And flash back to 3.5.5 on both TX and RX via USB/Passthrough

[old cape]

Hey! I’ve updated everything to version 3.5.5, but I’m still facing the same issue. Here’s exactly what I did:

HappyModel TX Update

1. I set DIP switches 1,2,3,4 to OFF and 5,6 to ON
2. Connected the HappyModel TX module to my PC via USB
3. Opened ELRS Configurator, selected the correct options (screenshot attached), clicked Flash – it flashed successfully
   4.Downloaded the generated .lua file from the Configurator
4. After flashing, I unplugged the TX and set DIP 1,2 to ON, others to OFF

TBS Tango 2 Update

1. Connected Tango 2 to my PC via USB
2. Copied the generated .lua from ELRS Configurator file into the SCRIPTS -> TOOLS folder
3. Disconnected Tango 2 from the PC

Receiver (BAYCK RC ELRS 2.4G-RX100mw v1.0) Update in Drone

1. Connected the drone to PC (with battery plugged in)
2. Opened ELRS Configurator, selected options (screenshot attached) enabled "Erase before flash" and "Force flash" and clicked flash
3. Flash completed successfully
4. Waited a few seconds, then unplugged battery and USB cable

Next steps

1. Turned on Tango 2
2. Turned on DJI Goggles 2
3. Plugged in drone battery
4. The RX auto-bound with the TX (solid blue LEDs on both RX and TX)
5. On OSD I see RXLOSS and BOXFAILSAFE when trying to arm
6. AUX buttons (like beeper) do work – drone beeps
7. OSD values from goggles:
   • RSSI: 80–90
   • RSSI dBm value: strange behavior – when I’m far from the drone (another room), the value is around 70 dBm; when I’m close, it drops to 10–20 dBm
   • Link Quality: 7:100
   • TX Uplink Power: 25mW

I’ve tested this with two separate Happymodel ES24TX Slim Pro TX modules, so I don’t think it’s a hardware issue.

Here is a screenshot taken after flashing the TX, RX, and Lua config and the drone is powered on and bound with the TX (They look pretty much the same as before flashing — the only difference I noticed is the letter 'C' in the top right corner instead of a -)

My receiver in drone:

and here is my configuration for tx and rx

btw When I moved far away from the drone (into the next room), the drone armed successfully. At that point, the RSSI dBm value was around 70 but when i come to my drone, i got rxloss

[frail vine]

Your reported RSSI dBm levels indicate that something is very wrong. That particular receiver is old and !unsupported. I would start by replacing that.