When i view multiple pdfs in Dopus viewer and use scroll wheel's tilt for next file - it hangs. (v.12.16.4)
That would most likely be an issue with the PDF viewer you are using. It is up to the viewer what it does when the mousewheel moves over it.
Try updating your PDF viewer, or an alternative PDF viewer.
(Also: Wheel tilt would not normally load the next file, only wheel scrolling would. And PDF viewers generally take over wheel messages to scroll the document, so the messages would not reach Opus and turn into a next/prev file, event even when configured that way in the basic image viewer.)