Page 427 of 2012-Grand_Caravan-OM-5th.pdf says:
Moving the shift
lever to the left or right (–/ +) while in the DRIVE
position will select the highest available transmission
gear, and will display that gear in the instrument cluster
as 6, 5, 4, 3, 2, 1.

However, mine only goes down to 2, and never to 1.
The vehicle is a 2012 with <700mi.

I first discovered this when trying to use low gear traveling down a steep hill, only to discover that 2 is not low enough to provide engine brake, thus leaving the only option of using the brakes.

Tried this with and without econ button on.

Is this expected, or a malfunction?

Have you tried to select 1st while not moving? Perhaps, your speed was too high to shift into 1st.