File list in Finder is missing files that actually exist

[mophilly]

I have been using NextCloud since it began, and OwnCloud before that. Still, there is much I don't understand. This is such case.

Server: NC 29.0.3 running on Koozali SME (CentOS 7)
About 40 active users, mix of MacOS and Windows clients
All use the NC desktop Client version 3.13.2

A new user uses MacOS Sonoma. The user logged on to the web app using Safari and, as invited to do so on the welcome page, downloaded and installed the Chrome Extension. As an aside, this user does not use Chrome for anything. Using the chrome "app" that appeared on his desktop, he attempted to edit a file. After some problems documented in other posts in the forums, he was able to make small changes. I recommended he delete the chrome extension and install the desktop client, which was done.

After that he added a new file. Now the problems begin.

The new file was created with the Apple Pages app. He dragged it into the local directory of the shared directory tree. For the record, this user is a member of a group and the group has all permissions on the shared directory and its sub directories.

The newly added file is not visible in the directory viewed with MacOs Finder on the user's machine. Using a shell session, the file is present in the directory. The file is listed in the browser app and was propagated to other desktop clients.

Permission on the invisible file are the same as other files in the local directory and the file name is not special. No period as the first character, for example.

Moving the file from the directory via command and forcing a sync did not resolve the issue.
Zipping the entire local directory tree, deleting the old top level folder then adding a new folder of the same name followed by a sync did not solve the problem.

I am wondering how to resolve this problem.

I suppose I could attempt to completely remove all files related to NC on the users system, run fsck and install the desktop app again. I have not found a concise shell script or instructions that would speed that effort.

Advice and links are greatly appreciated.