I found this as well, I noticed that it almost never catches on fire when there is a lava block right in front of the dispenser, but it does catch on fire when there is at least 1 air block between the dispenser and lava.
I found this as well, I noticed that it almost never catches on fire when there is a lava block right in front of the dispenser, but it does catch on fire when there is at least 1 air block between the dispenser and lava.