Ok, I just tried again and it printed error this time and gave me a Error message.
Edit: It seems last time i tested it i didnt get any messages or anything because i place the burger somwhere the box trigger didnt extend to. So i fixed that, I set the Cooking print to false and it worked but.The same thing is happening that usually does. It cooks ones that are no where near the grill while leaving the one on the grill uncooked.
That error means that the the “Grill” variable isn’t actually setting to the Grill BP. That’s a fault on my part, I’ll try and find out the cause / solution for that.
It’s super-odd that the ones that are not on the grill are cooking, they shouldn’t even react to the trigger. Are you using child BPs or exact duplicates?
I placed one and alt and dragged them all over. Right now i have 3, Burger 1,2 and 3 if i put Burger1 on the grill then Burger2 will cook. If i put Burger2 on the grill Burger2 and Burger3 will cook.And if i put Burger3 on the grill nothing happens at all.
Right, this sounds mighty weird. I’m going to create a project myself to see if I can fix or at least re-create your issue. If I come up with a solution, I’ll post the project here & BP.
Give me a couple minutes to do all this though!
Do you want me to send my blueprints?
Nah, it’s alright. It’ll better to do it from scratch. I’m about 70% done (Inc Uploading) - This is because it might be something in one of your Blueprints causing the error, but it might not. Hence why I’m going it “How I’d do it”. 
Ok, Thanks 
Done! Just uploading now, won’t be long. I’ll post the blueprints when I get a spare moment but anyone is free to download the project (When it’s uploaded). It was quite a fun little project!
I didn’t get the same error as you, but when you take a look inside, you’ll see why (I kinda cheated ;))
Looking forward to it 
MY VERSION IS READY FOR YOUR FLIPPIN’ GAME.
Download Link: CLICK ME
There you go, Problem solved. (…Hopefully)
Also had a little fun while I was it:
Controls:
Left mouse button - Pick up / Drop Burger
Right mouse button: Poke burger / Launch burger
**Cooking: **Every 3 seconds the burger changes state. It’ll burn and then it will catch fire, so be careful!
I took a break from writing my two books and working on my game to make this, but I hope it helps you out in some way, it was extremely fun to make & play around with!
Video (For those who don’t want to Download):
https://www.youtube.com/watch?v=-E00iAG4AbU
** BLUEPRINTS SCREENSHOTS COMING WHEN I CAN GET A SPARE MOMENT**
Thanks this helps alot
Not a problem, Glad I could help! 