Using Windows 4.6.2 Base Camp. Was swimming along entering manual UTM coordinates eg, 7 W 464202 7672389, and Locate Coordinates accepted the entry UNTIL it started to convert each manual entered coordinate to N. On a Position edit Base Camp will not accept a W and converts all manually entered coordinates to N. (some place in the pacific ocean vs. where it should be in AK). I've reinstalled the software and wore out the forums search. The was a 2011 post that identified the problem but got no response. Thanks.
After selecting the Edit functions for UTM grid, coordinate entry and recentering seemed to work for me near the point referenced by the OP. I have little use of UTM coordinates, but have dabbled and have noticed in a different application than BaseCamp that leading zeros (and other digits) can be tricky due to geometric truncation of the metric linear (as opposed to angular) measurements.
As the user approaches the poles, fewer and fewer numbers are valid in the UTM grids. This issue may be more evident in the southern hemisphere. Being able to actually see the grid zone layout overlay does help in understanding the potential issues. Good luck.
Simplest solution shouldn't be the last the try....I realized out of 50 coordinates I was entering, the one I kept trying over and over was missing a digit. Works fine. Thanks for input.