3ds Max SDK: UV Channel 2 resets after “Abandon”

[MSFS 2024] Bug Reports SDK: Tools/Samples/Documentation
1

  • SDK Version: 1.5.7

  • Frequency: Consistently

  • Severity: Blocker

Bug Description:
In the latest MSFS 3ds Max SDK (and possibly earlier versions), switching to UV Channel 2 triggers the prompt offering two options: Move and Abandon.

Expected behavior:

  • Choosing Abandon should allow switching to UV Channel 2 without moving/copying UV Channel 1 data into Channel 2, so both channels remain independent and editable. This is critical for workflows where UV1 and UV2 must remain separate (e.g., different mapping purposes).

Actual behavior:

  • When selecting Abandon, UV Channel 2 does not persist correctly. After switching away and returning to Channel 2, the UVs on Channel 2 are reset/lost, as if the channel was never saved. This makes it impossible to iteratively author UV2.

Impact / Workaround:

  • The current workaround is to bake the result, but baking is destructive for iteration: if we later need to revisit or refine UV Channel 2, we risk losing prior UV2 work when returning to that channel.

  • This blocks normal production workflows that require repeated edits to UV2 over time and makes multi-channel UV authoring unreliable.

This appears to be an SDK/tooling regression or a broken implementation of the Abandon option and should be fixed so UV Channel 2 is preserved and editable independently after choosing Abandon.

2

I’ve dealt with this exact bug going back to 3dsMax 2008 - the workaround I’ve always used is treat switching to UV2 as ‘one way’; abandon UV1→ edit UV2 as required → collapse stack with UV2 still selected. If you need to go back to UV1 you can re-add the unwrap modifier. It’s not ideal but 3dsMax has a ton of issues with preserving interim data like this, vertex colours, node names etc.

I doubt Asobo has much influence on this from my experience at least.

2 Likes
3

That is exactly what I found works too. Collapse and if you need to make a change then add the UV modifier then abandon to UV2 again.

But this was working several version ago or back in 2020. So for me this is the first time I have ever encountered this.