Both of these flavours seem to make sense as a potato chip flavour. I have had chips in the past with a butter flavour, but soy sauce is a new one for me. Having said that, I can't see why soy sauce wouldn't work. The butter potato chips I’ve had in the past worked fairly well, and I also like butter on my baked potato, so you’d think there’s nothing to worry about. The strange thing is, these chips taste weird.
One of the key things that make these chips a little strange might be the combination of these two flavours. Only recently have I ever had these two flavours together outside of the candy world. It was in a bowl of ramen that was buttered corn flavoured. In the case of the ramen, the flavour combination worked really well. The reason why I don't think it works with these chips is the imbalance of the two flavours. The minute you open up the bag you're immediately assaulted with a butter flavour.
It's a really strong butter flavour, and there's almost no sign of the soy sauce at all. It could be that the soy sauce is providing the saltiness of these chips, but you would get the same effect if you used a salted butter. The butter is the star of this show, and it doesn't totally work. I think another thing that might have made the ramen work but not these chips are the addition of other flavours, such as pork and assorted vegetable (most notably corn). The plain potato flavour is a great canvas for flavours, however it doesn't really add that much to the chip itself. You need to balance the flavours you use on a potato chip for it to work, unless it's just salt and oil where the potato can shine on its own.
Add just about any other flavour and there might be a balance, butter on its own does not work.