MyCloud Web access does not show all files

I use a PR4100 system with up-to-date OS5. When accessing my files via iOS App (WD MYCloud) or via Webbrowser, I will not see all files. It seems that the latest date of files shown in from December 2020. In Windows Explorer I can access all files as expected. I have logged off and logged on from and it did not help. What do I need to do, to see all my files in the iOS or Android App from MyCloud? Thanks.

All files and folders will not be seen in the client apps until the indexing and generating previews process has completed.