Welcome to our new forum platform. We realize there is still some work to do and we appreciate your patience. Please let us know if you have any ideas or suggestions: email@example.com
Mercator settings from .PRJ
I shouldn't really call this a bug, since .PRJ files are inevitably approximate.
The issue is that for Mercator projections, GM 12.01 (and previous versions) overlooks the True Scale Latitude parameter written in a PRJ file (for some reason) as standard_parallel_1. It always defaults to 0.
This is the case even for .PRJ files GM has written itself.