finder does not show all files from NAS

Sorry this is a repeat of an unsolved but archived problem.

For some reason the mac finder does not display all the files in the directory even though the files are there (i can see and open them when accessing the NAS through the PC).

Files were visible but a directories created, and the files moved into those directories using windows 11 commands (ie opened command window and used mkdir and move commands). Directories are visible but they appear empty in finder.. VERY DANGEROUS because cleaning up 'empty' folders would delete the files you can't see. Files remain visible from windows.

Also, on occasion some of the files are shown as a folder than a file in the finder. E.g. a clip called last_holiday.mpg might show as a folder (when you open it it is empty) rather than a media file.

Files are not flagged as hidden. Turning on show hidden files, does not make them appear.

Is this a bug or is there some wrong setting?