Sound is not my strong point, but I do know there are some peculiarities about sound in native Decker that are a little different in Web Decker and (temporarily) using the browser-based Web Decker to import your sound clips might be the easiest workaround for mystery audio problems.
You can either open your project in Web Decker to import them before saving the file and re-opening it back in native Decker.
Or you can import them into a blank Deck, save it, and transfer the audio clip to your active project using the File > Resources menu.
(Or by dragging the other .deck file onto your open Decker project from a folder -- that will also open the same resource transfer window)
Another interesting thing about Web Decker is that it supports any audio file format your browser can handle, it's not just limited to .wav files. This might also be easier in some ways if you're having to convert clips anyway.
Hopefully this helps in the short term! If there's still issues please say so and I'm sure someone with more audio experience can help.