Hello
Tried on R16 on Windows ; as for you, after restoring the layer, toolpath are not generated (but the right IDs are still in the MOP ID property) and a warning is displayed in the log windows
If I add a new geometry, I get a correct ID (ID = 1 in this case) but not with a second (#2 as one existing object)
If I undo, the (wrong) geometry #2 is removed as expected .. and now, if I generate toolpath, that works ...
++
David