For those troubled by this bug. I have a workaround.
1) After creating the .csv file, open it in Excel.
2) Do a find/replace for the leading spaces in longitude column. (in cell a1, highlight the spaces before the longitude numbers.)
3) Then ctrl+c to copy.
4) Then highlight column A (longitude column).
5) Then open find/replace (ctrl+h)
6) Paste the spaces in the Find box
7) Make sure the Replace box is empty.
8) Then Replace All.
9) Then in column E put in =clean(a1)
10) Copy that formula all the down as many rows as needed to clean all the longitude numbers in column A.
11) Then highlight the cells in column E with the =clean formulas in them
12) Do a copy and paste values for those cells
13) Then do a cut/paste of the column E longitude values into column A

I suppose you need some Excel skills to do this, but if you can do it, you will now have clean longitude values. The file will now work when using Garmin POI Loader.