see title. 1.8.1 features fenceposts in mineshafts. If a drill comes directly on top of a fence, it will mine it. If it is adjacent it will stop until you remove the offending fence or reposition the miner directly over it.
QuotePump/Miner Combo stopping after it extracts a lava block and requiring the mining drill to be removed and replaced, releated to Pumps being too slow
still exists
Quotemining bedrock
haven't seen this though it isn't marked as fixed in the sticky.