The DEM is probably okay as long as there was enough information for it to be generated and there aren't big smooth areas devoid of detail (like what happens near trees and along the edges sometimes).
Your recent flights in Flight Sync have a ton of signal dropouts. These could be because of a hardware issue, poor antenna pointing or RF interference. It is also possible you had another drone related app running at the time.
Had your connection been good, if you updated it to a faster write speed that could be the issue. The slower write speed is the safer thing to do.
It is always good to check the map at the bottom of the upload page in the DJI specific workflow to make sure the image location dots look correct.