Live mesh warp in Photo disappears

[Kasper-V]

I'm preparing some images of mouth shapes for a video. Last night I put the upper and lower lips in groups (along with tongue & teeth) and applied a live mesh warp filter in Photo to each to form the various letter shapes, and saved everything. This morning I find the meshes seem to have disappeared! No nodes or lines appear when I try to edit them, and the warped image is not showing. When I turn off the mesh the original image is still there.
What's happening? Can I restore the meshes, or must I delete them and reconstruct them? (If I do, I'll have to rasterise them, and lose the ability to edit later.)
There are ten to twelve pairs of shapes for four separate characters, so you can see I'm reluctant to start all over again.

The top image shows the default mouth shapes with no warp applied. The middle one shows the 'W&Q' shapes with the meshes turned off, and the bottom one shows the same with the upper lip mesh turned on: the image disappears (revealing the colouring for the inside of the mouth).

[Ldina]

@Kasper-V For me, double clicking on the Mesh Warp icon in the layers panel re-opens that filter and makes all the nodes available. Single clicking doesn't do anything, whether I have the Move or Node tool selected.

[Kasper-V]

Mystery solved! I resized the images -- the sources were all different sizes and bigger than the target app. The meshes stayed where they were and didn't resize. 😕
Also, Undo doesn't remove the mesh, only the changers made to it.