Actually, no need to send anything, the issue of missing map icons has been fixed in the new 4.5.0 release which is out now! Forum thread with more information: Mapillary Desktop Uploader 4.5.0 is out now, with new editing features!
We have made some changes how the map markers are shown in order to make moving images on the map easier. From now, the active image marker will be always visible while the other images will have a marker only when hovering over them. Let us know if you have any feedback, thanks!