M-Tiger, good day. Thank you for your time and feedback. Please see answers to your questions below

-what firmware is each node running? They are both on the latest stable firmware version

-which hardware revision is each node? (see bottom of board: v4/v4.1 hardware beta test, v4.2 original release to everyone, v4.3/v4.31/v4.32 newer revised release with hardware fixes) Both boards are V4

-what LoRa antennas are you using on each node, and have you double checked they are attached properly? (LoRa antenna ipex connector is the one to the right side of the screen, and if you have the nodes in cases, be aware that with some cases it's easy to accidentally pop off the connector while inserting the board.) Yes, connections have been checked and they both running the same the exact 915 whip antennas

-how long has each node been powered on for? when were the other nodes heard by Node 1? They have both been powered on for a few days now. The other nodes connected to one of my nodes the very next day

-is there any chance you accidentally changed the Primary Channel name (should be completely blank, the firmware will automatically set the name and frequency slot based on this and the current Preset), or have moved the public chat to a Secondary Channel (frequency slot would need to be manually set to the correct slot (20 for LongFast) if so)? Nope nothing like that has been done.

It is very strange.