Uploading large files

NetDrive version: 3.6.510
Windows/Mac Version: 10
I was transfering from my hard drive to my webdav mapped folder a large quantity of files, and in the same time I was renaming several files in one folder from the webdav mapped drive. Because it took to long to copy the files from hdd to weddav drive (over night), i wanted to cancel the transfer, but the the transfer crashed. After that I realized that renamed files are missing, even if they were on the same drive.
What happened? Where are my files?

webdav mapped a synology NAS folder