I got two exactly same hardware, installed same ESXi version. Somehow cloning from other ESXi to one server was working, but another one always failed at 33%.
It only impacts to existing VM cloning but not impact to new created virtual machines. I spent lot time on the troubleshooting. We replaced cables, switch ports, reinstalled ESXi.
There was no abnormal logs except following:
2017-11-15T05:47:36.023Z [FFF001A0 verbose 'NfcManager' opID=F39DF7E6-00002211-da-c-bf] [NfcClient] Closing NFC connection to server 2017-11-15T05:47:36.023Z [FFF001A0 warning 'Libs' opID=F39DF7E6-00002211-da-c-bf] SSL: Unknown SSL Error 2017-11-15T05:47:36.023Z [FFF001A0 info 'Libs' opID=F39DF7E6-00002211-da-c-bf] SSL Error: error:1409E10F:SSL routines:SSL3_WRITE_BYTES:bad length
VMware support eventually provided me following KB to workaround the problem. Looks like it’s a bug on ESXi 5.5 2068190.