Hi, on both my Macs (iMac & Macbook Air) running 10.11.4 they won't pair with the Logitech unifying software. I'm trying to pair my Performance Mouse MX mice (2, 1 on each computer) and the Logitech K750 keybord. I've updated the software to the newest download, but it simply won't pair. Do you guys have any suggestions? Thanks.