Can't dismount off a tamed, saddled horse

So i tamed a horse and put a saddle on it. i rid it around, and dismounted once, i attached a rope to it and tied it around a fence. Then i mounted it again and could no longer dismount. This is on a multiplayer Server. (Lan)

I've tried L-shift like it says and nothing happened. I tried taking the saddle off, disconnecting, and reconnecting, and pressing every button on my screen although nothing is happening. I do not have the Mo creatures mod.

Steps to Reproduce:
1. Tame the horse
2. Saddle it, take it for a ride
3. Dismount, attach a rope and tie it to a fence
4. Mount again (the rope was still attached)
5. Try to dismount with the L-shift button