Status Emails Invalid Digital (signing) Certificate

While it looks like the IPFire Status Emails add-on may have been abandoned (no github activity for several years), it still works (mostly) flawlessly and provides me with a daily report of general info/health of the system. However, one thing has popped up and I can’t figure out how to fix it.

Several weeks ago, I started getting “Invalid Digital Signature” errors in Thunderbird (IPFire *.asc key has been imported into OpenPGP Key Manager). The message is still encrypted so not a huge deal but I’d like to determine what is causing/fix the bad signature (I have regenerated the signing key via the WUI, still receiving Invalid signature errors) if possible.

Any insight greatly appreciated.