Odd Galaxy Progress Screen

I play on Xbox, and every time I check my Galaxy progress, I see numbers such as “100/95 Missions”, “60/46 Fast Travel Stations”, or most troubling (for me) “36/30 Erdidian Writing”. While the progress screen is an issue in itself, but I have no idea how to track the number of Eridian Slabs I have decoded, which is holding me back from getting the “Tales From The Eridian Slab” achievement. Anyone else notice these funny improper fractions?

How do I see eridian slab progress?