iPad version 1.0.10
Please see attached screenshot.
My steps:
4 equal squares.
Wanted to swap top and bottom (to see how pattern aligned).
Moved topleft 4 part down (to still have a grip on it after moving 5 to top)
Moved 5 to top.
Moved 4 to bottom. Layer thumbnail in Palette showed it still at part-way down.
Closed palette, switched and moved other layers: no change to thumbnail.
Closed file.
Re-opened to find thumbnail still at half-way, but layer content (4) had disappeared. Not hidden under any other layers.
Nothing restored it. Thumbnail remains even after closing, re-opening file.
Can't say if/when AutoSave happened, but at no time had I deleted the Layer 4 anyway.
(Have noticed before Palette thumbnail does not update, but never known layer to disappear).
Hope this of use.
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ALSO (while on the subject) ...
2 Suggestions for Layers...
...Ability to select (Layers Palette) more than one Layer - other than having to make Group, individually move into Group (and then maybe later unGroup).
...In Select Menu, a command to 'Select Layer' (Active Layer).