In our realm we have chain commands blocks hooked up to repeating command block that need redstone.  The command blocks spawn tnt in certain locations around our island.  We made sure one person was on the island and one person was there with the command blocks.  The tnt only spawned at the location we set the repeating command block to spawn the tnt.  All of the tnt should spawn in the same chunk since the island isn't that big.  The chain command block would not activate and listed itself as impulse command block as shown in the screenshot below.  We gave ourselves a fresh new chain command block and it still listed itself as an impulse command block.  This is definitely a bug because in a previous version when we tested the same thing the chain command blocks worked perfectly fine.  I hope this bug will get fixed.