it is a puzzle…
i exploded the image and all the cut looked set to 3/4 of an inch to me. Like i said before though v carving I think v carving will set the depth according to width of cut so at least the depth should be consistent across all the lids.
The diagonal cut you made seems like a good test of the setup… if the board you did that on is even thickness and held down evenly?
i wonder, it looks like you have the lids set in something, a board with round cut outs to hold them while they are cut? if that’s the case is the holder you are using true?