Champion Movement Bug: Makes Games Unplayable

So, I had the weirdest bug just happen to me. It didn't break the game, or cause the client to crash or anything, but it did make the game unplayable. Here's what happened.

So, I started the game, playing as Leona, like normal. It took a quite a while to start the match, and I was worried that the client had crashed. So, I mindlessly started clicking around on the screen when, without any changes to the loading screen, I was whisked into the game. About a minute had already passed once I got into the game, which I thought was odd, but I bought items and spent my ability point as usual.

Anyway, once all that was done, I tried to move. This is where things got weird. I'm not sure if I tried moving as minions were spawning, or when the announcer said that they were, or at another random point entirely, but at around the 1:30 mark, when I clicked on a point in bottom lane on the mini-map, I started moving toward mid lane.

At first, I thought that I had simply misclicked, and tried moving toward bot again. No luck. I tried multiple times, but I was stuck moving from our base to their base, just like a minion. When I tried clicking on a point on the ground nearby, just to see if I could walk there, the green circle that indicates where your character is going did appear, but Leona still didn't move from her path toward the enemy nexus. I could still recall, use my abilities and drink my health potions, but I couldn't go anywhere besides down mid-lane toward the enemy base and I couldn't attack. This bug literally made the entire game unplayable, and it didn't even have the decency to crash the game, so I had to manually quit, and I'll probably get a warning from the Leaver-buster system which literally no one likes...but I digress.

If someone from Riot could take a look at this and figure out what caused it, that would be greatly appreciated. If anyone wants more information about what happened, I'll be happy to comply. I just don't want this experience to happen to anyone else.

As a final thought, has anyone else experienced this glitch? If so, was it a one time thing or did it keep happening?

Thanks for reading.