This is how this feature works:
Assuming you already have a set of numeric map coordinates (Latitude and Longitude) for some or all your data
These two coordinates have to be in a valid numeric format (it is the only way it works)
example of valid numbers: 43.450471, -79.200666
but not in other formats like
43.450471N, 79.200666W << invalid
43°27'01.7"N 79°12'02.4"W << invalid
Latitude must be a number between -90 and 90, excluding the extremes
Longitude must be a number between -180 and 180, including the extremes
You need to add a couple of extra columns (Latitude and Longitude) on your Data sheet, and enter your coordinates there. The headers (usually in row #1) for these two extra columns must have exactly those names: Latitude and Longitude
Alternatively, if you already have the Latitude, Longitude a single column separated by comma, just name the header of that column as LatCommaLng and that's it.
The column you select for Location (Address) in the sidebar dialog will only be used if there is no Latitude / Longitude values for that particular line
The table below is a valid example from a sample spreadsheet
in this case, the add-on will use the provided map coordinates (Latitude and Longitude) for Miles and Ferguson
but calculate (Geocoding) the coordinates for the other three addresses.