After following the sticky post above and updating the repository key, I ran an apt update. There were updates for wine-staging, so I went to install them. Then I was "greeted" with the following error:
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
libavcodec-extra57 : Conflicts: libavcodec57:i386 but 7:3.4.4-0ubuntu0.18.04.1 is to be installed
E: Broken packages
32 and 64 bit packages of the same library need to be the same version. Apparently you have a version of libavcodec installed that is not the same as the i386 version apt can find. You need to either change your installed version to match the i386 version or find an i386 package that matches the version you already have.
Update: I'm not sure what tomfoolery was happening, but this wasn't a WineHQ thing. This was an issue that seemed to have appeared out of nowhere with Ubuntu's repositories. just installing libavcodec-extra57:i386 (which also pulled in several other i386 libs) seems to have fixed the problem. The winehq.key update was simply a weird coincidence. Not sure why these libs weren't already installed or why they "waited" to cause a problem until now