So this is the lenxyz_nominal bug. If you are not using Attribute Inspector (by @Aerilius) and Attribute Helper (SKP Team) you should get them. There is a LOT more going on with DCs than shown in the SKP DC attributes panel.
In this case the _last_lenY is out of sync with the LenY and _leny_nominal attributes. Don’t completely understand how/why this happens after having spent a ton of time looking into it, but it has to do with handling transformations I think. It is a patch on a patch according to @DanRathbun. Either manually fixing the geometry or deleting the leny_nominal attribute (it gets rewritten correctly by the DC extension and updates the other 2).
Here is the fix: