I had something similar originally with my MyCloudMirror - it was only visible to QuickView on certain machines, and on others it was intermittent or only partially seen (not all options were available).
In my case it turned out to be the speed of my network, fundamentally down to a router that was getting rather past its best. Updating that to a newer and faster model solved all of the issues I was seeing, and my MCM is now fully visible from all machines.
Are your symptoms anything like that, for example seen by LAN cable-connected machines but not by wireless-connected ones, or not seen when there is a lot of network traffic going on such as streaming or similar?
