My Thresh just disappeared o.O

[GAMEPLAY] Thresh goes invisible for a few seconds after going in with his hook and using his e.

I can't really explain what happened here but my teammate Thresh lands a hook on the enemy Varus and goes in. Then, after reaching Varus, he instantly casts his e and goes invisible. As you can see in the video, though, he still shows up on the minimap and uses his spells but I can't see his champion model. I acted pretty normally to this because I've seen tons of videos with the same bug. However, this one is different than the others. From the videos of other people's experience with this bag, the champion didn't just disappear but he also couldn't do anything (cast spells or move), so I started backing off, thinking that I was placed in a 2v1 position. While I was backing off, he threw a lantern at me and that part just got me super confused.

This is the first time that I've encountered this bug personally in my game, so can't really provide any more information than the video and my poor explanation of what happened in the video. Oh, and I didn't see that happen again in that game as long as I'm concerned. (Now that I'm thinking about it, I should've asked the enemies if the same had happened to them but I'm pretty sure they would've said something in all chat if it did.)

Hope this gets looked at ASAP because as funny as the bug is, it can be quite sudden and confusing for your teammates.