Empty oil filter

[LongRanger_imp]

I came home from a ride a few days ago and drained the oil within minutes of parking the bike, while it was still very hot. I couldn't get the filter off, so I simply reinstalled the drain plug and left the engine unfilled. I bought a new filter wrench but didn't remove the filter until today. I expected it to be partially full of oil, but it was completely dry. Very odd! I removed the drain plug again, thinking perhaps the oil had drained back into the crankcase, but it was dry too. I've never experienced anything like this before!