Hello franz,
you can mark the points in 3D view with Point Lasso or Point Rect tool (in the Alignment tab) and then press Find Images. This tool selects the images on which those points are detected.
Did you group images by exif before the alignment? This might help to align them properly.
Regarding the cam images, did you make sure that you have sufficient overlap among the images? You can try to place some control points on both drone and camera images and align again. You can also try to raise the Max features per image and Preselector features a little and change Image overlap to low in order to help merging.