Animation markers deleted after re-import #124553

Tested versions

• Reproducible in 4.7.2-stable and 4.8-beta1

System information

Godot v4.7.2.stable - CachyOS Linux #1 SMP PREEMPT_DYNAMIC Fri, 09 Oct 2026 15:36:46 +0000 on Wayland - Wayland display driver, Multi-window, 1 monitor - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 5090 (nvidia; 615.78.08) - 13th Gen Intel(R) Core(TM) i7-13700K (24 threads) - 62.54 GiB memory - PulseAudio (44100 Hz, Surround 7.1)

Issue description

When importing a glb file with an animation, if "Save to File" is enabled and "Keep Custom Tracks" is on, while markers are saved to the file when you create them, if you reimport the glb file, the markers are deleted from the file.

I could see an argument that the "markers" are not "custom tracks" and so the "Keep Custom Tracks" shouldn't be expected to preserve them, but it seems as though they're similar enough to custom tracks that they should be preserved. The fact that they are saved to the file in the first place makes me think this is an oversight.

Steps to reproduce

1. Add a glb file with an animation to the project.
2. In the Advanced Import Settings, ensure "Save to File" is "Enabled", "Keep Custom Tracks" is checked, and a Path is set.
3. Go to the imported AnimationPlayer in a scene (add the glb to a scene and check "Editable Children", or create a "New Inherited Scene")
4. Add a marker to the animation and save it. Optionally also add a custom track to it.
5. Close the scene.
6. Reimport the glb file
7. Open the scene and the markers will be gone. If you created a custom track in step 4, it will be preserved.

Minimal reproduction project (MRP)

MRP.zip

If you look at "dummy.tres" in the project before opening it, you'll see a "test_marker" defined on the animation. Once you open the project in godot and it does its initial import, the "test_marker" will be deleted.