ZWO ASI1600MM-Cool Image Download Hanging

More info
Also hangs on first download or after first download with ASI178mc
Works fine with Canon T3i
log has lines (exposure is 5s, I kill sequence after 30 s with no activity):
[6/11/2016 12:44:34 PM] [DEBUG] [Sequence Thread] Entering super dangerous loop to await image completion...
[6/11/2016 12:44:34 PM] [DEBUG] [Sequence Thread] TEMP - Current Event16: 0
[6/11/2016 12:45:06 PM] [DEBUG] [Main Thread] User requested sequence abort...