I got a gold key from the weekly so of course I wanted to use it and what happened is after awhile I reached a wave of zombies and most of them were killed by my Photon Blast (Julius Nifta) but about three or four of them survived and I couldn't kill any of them. Thinking that it was lag I just waited around and then a few minutes passed and nothing happened, I was taking one damage every so often from their attacks but most did nothing, and I even fed my mag just fine as well so the quest bugged out and I was forced to close the game losing my gold bonus key. Here is a screenshot of what it looked like.

Personally I have a single pair of Jet Boots and multiple Blades of different elements depending on what I am fighting. Sub palette one is Resta, Trimate, Break Stance, Switch Strike, Summoner's Mark, PB, Shifta, Deband, Megiverse, and Moon. Two and three are basically the same but with PB Restorate Field taking Break Stance's spot, and Blade Fever / Rapid Boost taking over Switch Strike on two or three respectively. I also switch Megiverse for the third sub palette for whatever tech the enemies are weak too assuming that they're not weak to fire, ice, dark, or light. Palette two also has anti over Megiverse.

Edit: I forgot that Shifta, Deband, Resta, and Anti do not change your Jet Boot element but still you should have a slot for a tech to change your element when need be.