For the Base, I did everything to get it back in a virgin state to reproduce the elevation issue.
I performed:
Factory Reset
Nuked the LittleFS
RTK FW Uploader => Erased Flash.
RTK FW Uploader => Flashed V3.3.bin
Power Cycled the PostCard.
After reading through this thread again, I suspect I had the Base Postcard in BASE mode when I first started the experiment (to enter my Fixed Coordinates)…since I was playing with a Base afterall.
As @amlago said, I probably should have started with the Postcard in Rover Mode to do that, which could have caused the problem.
So, with the Fresh PostCard, I confirmed it was in Rover mode before making the changes with Serial Config.
I got everything like I wanted it, paired the ESP-Now Radios, then switched to Base Mode afterwards. This worked flawlessly, no issues with Elevations. Anytime I power up the Base, it just starts working and the Rover is in RTK fixed mode quickly 
I repeated the Factory Reset and performed the same setup procedure but started out with the virgin PostCard in Base Mode (expecting this to cause problems). I still cant reproduce the Elevation errors.
I’m working this poor little PostCard to death (see this post), and it’s doing an amazing job !
I think a Mod should delete this Thread to not scare away any potential Base/Rover ESP-NOW users. It works great, and I have no idea how I fouled-it-up on my first ever attempt.
I’ll start a clean thread later, without all this nonsense I created somehow 