Why aren't some images showing when I Run on Device with GWD?

[AC Question]

I'm using Gear Watch Designer, and I've recently made a new watch face. It runs and looks normal when I do a standard Run (F8), but when I try to Run on Device (F9) some images that I have imported are not showing up on my Gear S2. Has this happened to anyone else? The images DO show up within the GWD application on the standard Run, but not on my own watch.