OneDrive container cTag property stopped changing

Hi,

According to the docs:

DriveItem - OneDrive API - OneDrive dev center | Microsoft Learn

"The cTag value is modified when content or metadata of any descendant of the folder is changed. "

I am using graph Api to monitor changes in one of my folders. Indeed this used to work as described but suddenly cTag property remains constant.

It will not respond to changes in sub folder files, adding files, deleting files or modifying fild in sub folders no longer causes the parent folder cTag to change.

Thanks,

Gary