I thought I was losing my mind. I knew I had just unlocked the side door of the Rolling Steel Tent, yet it was still locked.
I unlocked it again, there was the clunk of the latch, but it remained locked.
Turn the key counterclockwise to open. Clunk. Still locked.
With the next attempt, I heard the unlocking clunk, but also a quieter clunk when turned the key to the neutral position to remove the key. Did it just relock?
So on the next try I left the key turned counterclockwise and, the door opened.
I watched the inside lock lever as I turned the key back and forth. Yup, the latch kept clicking to locked position when I tried to remove the key. So I tried holding the lever as I turned the key. I could remove the key, but as soon as I let go the latch flipped to the locked position. Ergh.
I worked the key and lever through several cycles to see if things would loosen up and act normally. No.
Okay, before I order up a new locking mechanism and tear the door apart to replace it, let's try good old WD-40.
I sprayed it in the lock, in the latch, in the lever and any hole or crack in the general area of the lock. And... it worked. All hail WD-40!