If one reads the My Cloud User Manual (http://www.wdc.com/wdproducts/library/?id=439&type=25) in Chapter 12 Connecting a USB Hard Drive, they’d find that it states the following; “You can attach a powered USB hub to the external USB port and attach up to seven USB devices to the hub.”
If one does a search they’d find this issue of multiple hard drives on a USB hub with some not being recognized has been mentioned and discussed before. Here is one such thread:
I mention in that thread of connecting four hard drives and three flash drives to a seven port USB 2.0 hub and the My Cloud recognizing and mounting five out of seven.
