If a hashboard errors-out for any reason during the tuning cycle, I think the Vnish firmware restarts the tuning process from the beginning. So if you have a board that occasionally has issues, it can end up tuning forever.
Your log shows some temperature sensor errors on chain 0, so my guess is that board is your problem. You might be better off trying to manually tune it from the "chip frequencies" tab.
And the log mikeywith asked for is different than the one you posted. The tuning log is not the "miner log", it is in the spot he indicated in his reply:
I can't tell for sure without seeing the tuning log, you can find them in Miner configuration > mining profiles > at the bottom of the page, copy and paste them here, please use the code tag when doing so, without it will be messy and hard to read.