I am trying to create a nice map figure with lat/lon frame annotation with the map composer. I tried following several tutorials on this and technically it works, however my problem is, that the frame annotation in both lat/lon is completely messed up: it is either centered on zero lat/lon or completely random mixed N+S for lat and E+W values for lon axis. In any way it does not match up with my actual map extent whatsoever and I have no idea why. In the item properties tab the image extents are the right values of my map extent, I did not change the CRS in the "Grids" tab ( it is pseudo mercator) I chose Map unit for interval units and experimented with the "interval" and "offsets", to no success. Settings for grid frame are zebra, left/right divisions: latitude only, top/bottom divisions: longitude only. in the draw coordinates tab: format: degree, minute, second, with suffix and I only enabled left and bottom annotations.
I am running Qgis 2.12.1 on kubuntu 14.04.