So I am having an issue when packaging a mobile map for offline viewing. This is a package that I normally do every week, but just recently I have started getting the Z value error

unfortunately the error message isn't very helpful, and the log doesn't show much either

Through trial and error I narrowed it down to one layer, and checking out the layer it doesn't have Z or M values enabled, yet I am still getting the error

I've tried creating a new feature class and copying records over, tried deleting the last 2 months of new/edited records. I've ran the repair geometry tool which fixed some lines with short sections, and one null geometry, but still did not solve the problem.
Any ideas???