I'm constantly having new images only partially downloaded from SD-card. Using option "Download New" shows correctly amount of new items (not verified) but very often leaves some undownloaded. Connecting to card again shows still new items, and correctly downloads them. I think this appeared after upgrading to 7.7.0 appimage version.
The import post process has been heavily revised in digiKam-8.0.0. I can't reproduce the issue with the developer version. I close the bug. Maik
Just to let you know this occasionally occurs in 7.8.0 too, but I will wait for 8.0.0. Just downloaded 157 images with "Download New" option: 136 first time. Feature shows correct number for selection but 21 was left unloaded.
Note : 7.x still maintained at least for one release 7.9.0 before to switch to 8.0.0. Gilles Caulier