The notice I received in the USCIS online status was incorrect, as there had not actually been an appointment scheduled. I think it is a glitch in their system, because it doesn't know how to handle a 319b application. I talked to a tier 2 USCIS agent on the phone and he basically ignored the statuses I told him and wouldn't address why they were wrong. He said the only 'legal' status update was the actual letter notices that were issued.
After contacting literally dozens of US Consulates and the few remaining USCIS offices, these are the only ones I found that would seemingly take fingerprints:
US Consulate in Lisbon, Portugal cooplisbon@state.gov https://pt.usembassy.gov/u-s-citizen-services/additional-resources-of-u-s-citizens/criminal-records-checks/
US Consulate in Liberia https://lr.usembassy.gov/u-s-citizen-services/local-resources-of-u-s-citizens/fingerprint-services/
USCIS office in Nairobi
However, I suddenly received an email a few weeks ago from Fairfax, VA USCIS office that said my naturalization interview was ready to be scheduled and that my biometrics could be done one week before the interview in Alexandria, VA. So this solved the problem for me. You may consider contacting them: WASOVERSEAS.319b@uscis.dhs.gov
Hong Kong 1 got a reaction from Chancy in Getting biometrics FD-258 appointment in HONG KONG for N-400 application under 319b