[XenonSurf]

There are some nasty differences between the 'normal' map and the tactical map, with the tactical one (TAB key) you don't have all map tools at your disposal. (Just one big difference I know, I'm now obset that coordinates are not shown, but I never noticed because > see just below.)

I switch to the normal map everytime with the 'M' key from any station. By doing so I bypass the tactical map everytime if I need all tools. I use the tactical map only when on the periscope to decide quickly which course to set for retreat or adjust for torpedo firing, I never use it for important things like marking target positions or drawing interception solutions, for that the normal map is best.
Try the M key and and tell if you then see the long/lat coordinates.

Have you guys set your grafic cards to 'Fullscreen with GPU' in the scaling options? This may also help displaying the coordinates.