why can't I all of a sudden not open my files or folders in iCloud?

I always saved a copy of any document I created in iCloud, but suddenly - only within the last few days it will not let me open any of my files in iCloud from my iMac

I access it via Finder and then by clicking on iDrive and then on the relevant application. I can make a copy of the file in iCloud, but even then cannot open the copy - howeverI can delete it i.e. move it to trash, so why won't it let me open it I wonder ???

Ps I have checked and I have no outstanding updates for any products

Justin