During months I've a context menu problem that I can't resolve until now. Due to the nature of the problem i thought it was a problem in my sistem. The problem is that the context menu isn't show when i sync with a folder in a external sd flash drive (what is very usefull in a tablet for example). Of course I've check all the context menu topics and confirm that the dll was perfectly registered. in fact the context menu works properly when I sync a folder in other drive. So I realised that the problem was in how windows 10 uses the external drive, the problem can be solved in properties -> hardware -> "unit"-> properties -> change configuration -> directives -> better performance. Before doing this the problem was resolved. I hope this can help to others.