I am struggling to pin down when this repros and when not. Image Size and how the mask is created seem to be affect it. But these steps do repro it.
- Create a new file in Photoshop - don't use a small one because this seems to work around it. I choose 6000x4000.
- Select one of the shape tools, e.g. triangle and draw a large shape on one side of the image. This should create a new layer.
- Select the move tool. Hold alt and drag the triangle to the other side of the image, so now you have two triangles each on its own layer.
- Select both triangle layers and either chose Convert to smart object OR rasterize layer followed by merge layers. Now you should have one layer with two triangles.
- Select pixels of this layer.
- Create a new solid color layer - make it a primary colour of you choice this should have the two triangles as a layer mask
- Select the layer mask and press ctrl-T to transform, right click the boxed area and choose warp
- Gridlines shound appear, drag one of them. The bug is at this point the mask "jumps" and/or changes size (but than can be warped) when it is expected to warp in-place.