Blendshapes Option in File->Export doesn't seem to work properly.

[ansuter]

Describe the bug I'm trying to select 'blend shapes' on the export window, and Maya consistently fails to export a simple blendshape.

file -force -options ";exportUVs=1;exportSkels=none;exportSkin=none;exportBlendShapes=1;exportColorSets=1;defaultMeshScheme=none;defaultUSDFormat=usda;animation=0;eulerFilter=0;staticSingleSample=0;startTime=1;endTime=1;frameStride=1;frameSample=0.0;parentScope=;exportDisplayColor=0;shadingMode=useRegistry;convertMaterialsTo=arnold;exportInstances=1;exportVisibility=1;mergeTransformAndShape=0;stripNamespaces=0" -type "USD Export" -pr -ea "C:/Users/ansuter/Documents/maya/projects/default/scenes/export-please.usd";
// Opening layer 'C:/Users/ansuter/Documents/maya/projects/default/scenes/export-please.usd' for writing // 
// Error: line 0: Could not save file "C:/Users/ansuter/Documents/maya/projects/default/scenes/export-please.usd". // 
select -cl  ;

Steps to reproduce Steps to reproduce the behavior:

1. Create a sphere
2. Deform->Blendshape
3. Windows->Animation->Shape Editor
4. Add weights, and key across any time range
5. Go to File->Export and try to save the usd

Expected behavior Export Blendshapes to work

Attachments Attached gif of process

Specs (if applicable):

• OS & version Windows 10
• Compiler & version N/a
• Maya version 2022
• Maya USD commit SHA: 0.8 tag (392b2fe07ad88a4866aac0f5f819cd5241fcbe31)
• Pixar USD commit SHA [e.g. dev at b85ddac2]

Additional context Tried also doing this via cmds.file, same issue

[kxl-adsk]

Thank you for reporting the issue @ansuter. Before we investigate, maybe @dgovil or @ysiewappl can comment?

[dgovil]

Can you try with ExportSkels as auto? AFAIK usdSkel requires that blendshapes live under a SkelRoot to function.

[ansuter]

exportskels=auto seemed to work fine! will pass that on! thanks!

[ansuter]

After making that adjustment, it does export (as long as mergeshapeandtransforms=0 or the sphere is under a group; as well).

edit: In Arnold, only the bounding box changes, but there's no mesh.

edit2: removed image and issue. turns out I was adjusting the wrong weights, hence why it didn't change shape in GL. Just seems there's an arnold usdview issue now.

[womanyoyoyo-adsk]

I think this could use a tiny bit of design to clarify that you need to have ExportSkels as Auto to get Blend Shapes to export. There is a tooltip but it doesn't seem to be enough. @santosg87 and I were discussing if this is a bug or if it needs design and we've decided to go the design route so I'm going to assign this to myself.

[psql]

I'm seeing the same issue, even with exportskels=auto enabled