Thank you! So somewhere along the way in one of the subsequent sim or world updates, 4W/22W and 8W/26W have been deleted. I know I’ve used 4W in the past in the JU-52, so I guess I should log a bug under the “Airports” category.
Thank you for confirming!
EDIT: I’ve added a bug report here:
Anyone else who enjoys floatplanes and misses flying around Oahu, or would like to do, please add your voice.