SUMMARY

When viewing an SMB network folder via kio, most of the files in the folder sometimes "disappear" on viewing. You can watch them go away one by one. I am not sure if this problem is occurring in dolphin or kio, of which I have 6.0.4. It feels possibly related to thumbnailing (which I have enabled for remote locations) as the files seem to disappear when dolphin attempts to thumbnail them and  there are often one or two files "left behind" that do not disappear, and when they are media files they will have correct thumbnails.

I am not sure if this should be logged against Dolphin or kio; I haven't seen it happen with kio clients other than dolphin but I'm not sure if I would have had the opportunity.

STEPS TO REPRODUCE
Tricky to reproduce as it seems to be intermittent. But try this...
1. Set up an SMB share (in my case from samba 4.12.8, unsure if this matters), containing directories with say 20-30 files
2. Add the smb share on another machine in Dolphin via kio, browse to a directory of files
3. In some cases, the files will disappear one-by-one before your eyes. If you go up a directory and then back into the one you were just viewing, all the files are back, but once again start disappearing one by one.
4. Which directories are affected seems to change over time, I haven't totally narrowed down the conditions but I suspect it happens when the network connection is interrupted and kio reconnects.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Fedora 40
KDE Plasma Version: 6.0.4
KDE Frameworks Version: 6.2.0
Qt Version: 6.7.0
Kernel 6.8.10-300.fc40.x86_64 (64-bit), wayland

ADDITIONAL INFORMATION

Disabling remote thumbnailing does not eliminate the problem.

This only occurs intermittently but it will be consistent for a given folder: in some folders the files disappear, in other folders they do not. Later on, perhaps after a reboot, a different set of folders have this problem.

The following is logged as each file disappears, with the path of the disappearing file:

dolphin: kf.kio.core: KFileItem: exists called when not initialised QUrl("smb://user@host.example.com/path/to/file.txt")
kioworker: kf.kio.core: An error occurred during write. The worker terminates now.

I have only observed this problem with smb; I also regularly use a webdav share by kio and have never observed this behavior. It also never occurs when the smb share is mounted to the filesystem via mount.cifs.

I fear this will be difficult to reproduce, but it happens very consistently with my particular setup. I am happy to collect additional information but I'm not sure how to get more useful output than what I included above.