I transfer 1.0/1.1/1.2 GPX files from my mobile phone to my Garmin Zumo XT using the Garmin Drive app. I haven't encountered any issues so far.
This is what i do:
copy/edit/create a route in the webbased MRA tool and have it saved;
Open my mobile phone and then open the MRA (Android) app;
Open the route i created/edited and select the share/download button;
The selecting the type of GPX file (i.e. 1.0 or 1.1 or 1.2 type) and press the download button;
In the pop-up menu i select export and in the next pop-up i select share;
in the share selection pop-up i select the Driver app
This app will then send the GPX file from my mobile phone to my XT via bluetooth/wifi/hotspot. And it is placing the gpx file in the correct path/folder.
Not sure if this will help you, but it is better than fooling around usinbg Windows Explorer and di some copy/paste actions hoping this will work out perfectly.