We have notified support about this. On the meanwhile maybe you should try contacting WD’s Technical Support about this. You can do so either by phone or email.
The store where i bought the device, and where i also reported my problem gave me this explanation:
“The problems between Apple’s OS10.10 (Yosemite) and the new firmware for the My Cloud EX2 is well known by Western Digital. Nothing else to do than wait for a solution supplied by WD.”
Whem do you expect the fixed firmware will be available? Please keep me informed on that.