[Isaac Sim 5.1] ZED extension stops working after the first simulation start: Camera not detected by ZED_Depth_viewer

[Alessio-Parmeggiani]

Hello, I am encountering a strange issue in Isaac SIm 5.1, I added a ZedX camera to the world and added the related action graph, when I run ZED_DepthViewer I can see all its data from the simulation.

After some updates are made to the world (adding objects, other sensors...), without touching the ZedX object or its action graph, the zedx stop working and I get this error when running DepthViewer:

[ZED][Streaming] No SHM-boost topic found for port 30000. Using UDP backend input.
[Streaming] Warning: Failed to retrieve camera settings from sender
[Streaming] Error: Stream Opening returned TIMEOUT (350)

I tried both IPC and Network streaming mode.
Do you know of any known issue that could trigger the error?

Isaac Sim Logs

Only the first I start the simulation since opening a file I get this error:

2026-03-05T08:49:25Z [1,159,012ms] [Warning] [sl.sensor.camera.plugin] Initializing streamer with ID 982 on port 30000
YUV encoding enabled, overriding RGB/BGR.
[Streaming] Use Transport layer mode : 2
[Streaming] Use SHM-Boost IPC backend
[Streaming] Error: failed to create RTP Session (err:-74)
2026-03-05T08:49:25Z [1,159,012ms] [Error] [sl.sensor.camera.plugin] Error during zed streamer initialization 0

All the other times this instead it says this. (after simply stopping and restarting the simulation).
[Port: 30000] Constructed annotator for stereo camera.

And some warnings or errors related to rigidBodies (pattern ...ZED_X' did not match any rigid bodies), I don't think they are related. Note that I removed the rigidBody component from ZED camera to avoid another error ( related to having a rigidBody attached to anothr rigidBody)

How to reproduce

I tried creating a new file and adding things one by one but I could not reproduce exactly when the sensor stop working, it seems mostly random. Moreover I got it working again on the same file wihtout changing anything but it worked only 1 time.
After the ZEDX stop being detected I could not restore the working sensor, even deleting all the content of the world and creating a new ZedX sensor and action graph don't work. It works again only if a new file is created.

I am using:

• Ubuntu 22.04
• Isaac Sim 5.1.0 (workstation installation)
• Isaac Sim ZED extension 4.2.1
• ZED diagnostic output:
  • Running ZED SDK Diagnostic : OK
    ZED SDK version: 5.2.0
    CUDA version: V12.2.140
    CUDA version: V12.6.85
  • Running Processor Diagnostic : OK
    Processor: AMD Ryzen 9 7950X 16-Core Processor
    Motherboard: X670 AORUS ELITE AX, Gigabyte Technology Co., Ltd.
  • Running Graphics Card Diagnostic : OK
    Graphics card: NVIDIA GeForce RTX 4080 SUPER
  • Running CUDA Operations Diagnostic : OK
    GPU 0 (NVIDIA GeForce RTX 4080 SUPER): CUDA operations working correctly

[Alessio-Parmeggiani]

I did some tests and found out some new information.
Currently the ZEDX works only the first time the simulation is started, after the simulation is stopped and restarted it stop working.

The error mentioned above:

 [Streaming] Error: failed to create RTP Session (err:-74)
2026-03-05T08:49:25Z [1,159,012ms] [Error] [sl.sensor.camera.plugin] Error during zed streamer initialization 0

Appears only if ZED_DepthViewer is open while starting the simulation for the first time.

Currently to use the ZEDX consistently I have to reopen the file evrytime I stop the simulation.

Changing the title of the issue to be more descriptive of the issue