I don't own an Atlas but the manual that came with my two 5in1 displays clearly mentioned the learning mode so I suspect, if it's not mentioned, it's not a feature of the Atlas.
On the 5in1's the learning mode works okay. Both of mine are within .01" of each other, often they match but both are about .1" lower than my Access, which is automatically adjusted based on my elevation and is usually within .01"-.02" of what the weather service is reporting. It would be nice to "correct" them up for that .1" but apparently it's not possible on the 5in1 displays.
Out of curiosity, when you first powered up the display what was the pressure reading with no correction? What's your exact elevation?
As far as the "forecast" feature goes, I would ignore it. My experience is that it's not reliable. If I could, I'd turn it off.