I’m an iPhone user rather than an Android user, but the location is the same either way, namely it’s \dropbox\Apps\RootsMagic\ But you have already confirmed that’s where RM8 put the RMGC file.
When RM8 creates the copy of the RMGC file, it doesn’t know or care whether the mobile device is going to be an iPhone or an Android. Since I don’t use Android, I can’t guarantee that the Android app doesn’t want the RMGC file somewhere else, but it wouldn’t make sense for it to be somewhere else.
I can run the Dropbox app on my iPhone and search for RMGC files. The first one that comes up is the RMGC file created by RM8. I would assume that you can run the same test on the Dropbox app on your Android. If you can run that test successfully, then then I’m not sure what else you could try. Note the this little test does not involve the RM mobile app at all. It just involves the Dropbox mobile app to the sure the file is on my mobile device.
I just ran one further test. My RM mobile app was still using the RMGC file put into Dropbox by RM7. So I tried the RMGC file put into Dropbox by RM8 in the RM mobile app. It came up just fine. As I was saying, the mobile app doesn’t know the difference between RMGC files created by RM7 or RM8. And when RM7 or RM8 is putting an RMGC file into Dropbox, they don’t know if your mobile device is iPhone or Android.