I'm trying to migrate an existing instal to my new 13in MBP. The old instal was 10.11. The MBP is 10.12.5. So I CCC'd the old install to a USB drive, upgraded it to 10.12.5, checked that it booted the old 2011 MBA OK but on the new MBP all I get is the circle with the line through it. i.e. can't find a bootable instal. I'm connecting the USB drive (Transcend 240GB Jetdrive) through a NONDA USB-C to USB converter. I get the same problem with a 10.11 instal on a different USB drive. I also get the problem if I connect either through a Belkin TB dock connected to the MPB with an Apple USB-C to TB converter. What am I missing here ? It has always (IME) been the case that the instal could be poured from one drive to another with CCC and it would still boot. This must still be OK I would have thought. Thanks.