Duplicate Finder MD5s all zero

https://www.haage-partner.de/forum/viewtopic.php?f=47&t=5330

Let's ask the devs, what could be the reason the duplicate finder shows an "all-zero" checksum for some (totally different) files?
Linked in the thread above are two screenshot of MikCha's problem, the dupfinder seems to group files for him, which may have same date/size, but their content is different (their MD5 checksum seems to be equal, but "00000..", which might be the underlying cause).

We tried setting the advanced setting for "max_md5_file_size", not sure if it should have an effect or not, for now it does not seem to have any, MD5 sum is still all-zero.

That looks like the MD5 may have failed for some reason. Are the files on cloud storage, in archives, locked by other software, or anything like that?

All these file will be stored on Synology NAS Folder and thhhe files are not locked.
The stupid databases of itunes, iphoto and aperture threw files together and destroyed the structure.

If you go to the folder those files are in, select a couple of them, and use Edit > Calculate MD5 Checksums, does that come back as zero as well, or do you get a different result?

Try turning off the MD5 Cache option in the Duplicate Finder as well; maybe it has cached zero checksums for those files for some reason.

To turn off the checksum cache will be get a better result.