Thank you for the system information. We have successfully ran 1060 3GB and 6GB under HiveOS 0.5-76 so we are really not sure why is this happening. Probably it is somehow connected to the number of the GPUs as all reports so far are with a lot of GPUs. Please try to add
-gpus 123 command-line parameter in your custom miner settings in order to use only the first three GPUs and see if this fixes the problem. Obviously this isn't a workable solution but it will help us reproduce it.
I tried on your advice - nothing has changed with 3 cards. The result is the same.