My ministry is currently performing some platform testing before we officially migrate from ArcGIS 10.3.1 to 10.5.1. Our group has been asked to participate and I noticed an issue when working with ESRI Grids in one of our native projections: NAD 1983 Ontario MNR Lambert. On 10.5.1, it can read the projection in ArcCatalog and even set the data frame in ArcMap to this projection, but when I add the grid into ArcMap, the projection reverts to the older projection name: NAD_1983_Lambert_Conformal_Conic. When I take it back to 10.3.1, the projection name has indeed changed to the old name. NAD_1983_Lambert_Conformal_Conic no