Harmonize not reducing cost properly.

Wild Ride's Harmonize cost is 4R. I had a 2 power creature, submitted it to be tapped to reduce the cost to 2R, and the game still tapped all 5 of my lands. Cost me the game. Feels really bad losing because of a bug instead of a play I missed or didn't see/ make. I knew the interactions and the system didn't respond as it should have.