I have a Redstone Mana Spreader with a bore/warp lens setup for automation of pure daisies. It uses the hour glass to time the spreader. If i have it converting stone or wood right infront of the mana spreader it works when i first set it up and stay online. If l log off the server and it stays chunk loaded. The mana spreader stops sending bursts. Also worth noting that i didn't quite set up the system quite correctly. even though it has a warp lens and its linked to the block.. the burst will fall short of the warp block.

The work around: If i make the conversion of wood / stone be one block away so there is empty air in front, then it stays working when i log off.