OK, an update after some more testing:
In 2020:
-- The HSI works as it should, however, the inop flag is showing even when it is working.
-- The LOC signal and needle keep working on the OBS #1 even when in NAV mode on an approach with the GPS.
-- The Auto Gear Extension seems to be working oddly -- it properly flashes when it is not engaged, but when under normal flight settings, if you engage the Auto Gear Extension switch, the gear will drop as if you are in slow flight, or have flaps, or have low MP settings.
In 2024:
-- The HSI seems to work fine during NAV or GPS mode, but then switches off when the GPS moves from TERM to LPV mode while on approach.
-- HSI glide slope does actually work when on an LPV approach!! -- but only when switched into NAV mode, which means the LOC needle stops working with the GPS.