I just got off the phone with Wahoo tech support and their first inclination was that my "maps" section needed to be updated. Evidently, even doing the regular updates prompted by the head unit doesn't always update the maps (pre-loaded or otherwise) that are in the head unit. It was my understanding that all maps came pre-loaded (which they do) and that any system update would also update the pre-loaded maps. Eveidently, managing maps and their corresponding updates is a process that needs to be handled separately from general firmware updates.

Tech support walked me through the map update process (easy peasy) and they asked that I go for a short ride to see if the problem is fixed. Wahoo also told me that in most cases when there is a hardware issue impacting elevation readings it's usually off by 10s of thousands of feet. Even though my elevation errors are large, they aren't large enough to indicate a head unit issue (at least not at this point).

I'll report back later today as to whether the software update fixed the issue. Fingers crossed.

I'd also like to add that dealing with Wahoo support is fast and easy (even thought it's been much more frequent than I would have preferred). They're easy to reach, they do their best to help you out, and they are quick to replace hardware if necessary.