Stream times out inside Plasma Bigscreen session

[korewaChino]

Is there an existing issue for this?

• I have searched the existing issues

Is your issue described in the documentation?

• I have read the documentation

Is your issue present in the latest beta/pre-release?

This issue is present in the latest pre-release

Describe the Bug

when switching to a Plasma Bigscreen session, Sunshine hangs and crashes when attempting to start a stream

Expected Behavior

The stream starts normally, as if in a standard Plasma session

Additional Context

No response

Host Operating System

Linux

Operating System Version

Ultramarine Linux 43

Architecture

amd64/x86_64

Package

Linux - Fedora Copr

GPU Type

AMD

GPU Model

AMD Radeon RX 580

GPU Driver/Mesa Version

Mesa Gallium driver 26.0.3

Capture Method

KMS (Linux)

Apps

Log output

[2026-04-02 15:13:43.585]: Info: Streaming bitrate is 1000000
[2026-04-02 15:13:43.585]: Error: [hevc_vaapi @ 0x7f5284049e00] No usable encoding entrypoint found for profile VAProfileHEVCMain10 (18).
[2026-04-02 15:13:43.585]: Error: Could not open codec [hevc_vaapi]: Function not implemented
[2026-04-02 15:13:43.590]: Info: // Testing for available encoders, this may generate errors. You can safely ignore those errors. //
[2026-04-02 15:13:43.590]: Info: 
[2026-04-02 15:13:43.590]: Info: // Ignore any errors mentioned above, they are not relevant. //
[2026-04-02 15:13:43.590]: Info: 
[2026-04-02 15:13:43.590]: Info: Found H.264 encoder: h264_vaapi [vaapi]
[2026-04-02 15:13:43.592]: Info: Found HEVC encoder: hevc_vaapi [vaapi]
[2026-04-02 15:13:43.592]: Info: Executing Do Cmd: [/var/home/cappy/.local/libexec/stream-start.sh]
[2026-04-02 15:13:43.710]: Info: Executing [Desktop]
[2026-04-02 15:13:43.764]: Info: New streaming session started [active sessions: 1]
[2026-04-02 15:13:44.750]: Info: Setting default sink to: [sink-sunshine-stereo]
[2026-04-02 15:13:44.751]: Info: Found default monitor by name: sink-sunshine-stereo.monitor
[2026-04-02 15:13:44.872]: Info: Opus initialized: 48 kHz, 2 channels, 512 kbps (total), LOWDELAY
[2026-04-02 15:13:53.769]: Error: Initial Ping Timeout
[2026-04-02 15:13:53.772]: Info: Setting default sink to: [alsa_output.usb-Focusrite_Scarlett_Solo_USB-00.HiFi__Line__sink]
[2026-04-02 15:13:53.891]: Info: 192.168.1.13: Ping Timeout
[2026-04-02 15:14:18.798]: Fatal: Hang detected! Session failed to terminate in 10 seconds.

Online logs

No response