One bit of info that was missing (or I'm blind), is the amount it should report after 1 cup of water.
Chatted with support, for the Atlas and its display (model 06061M - still confused why the display mattered), they said it should report 0.61" of rain after 1 cup of water (over a 20+ minute period).
The 5-n-1 and the rain gauge suggested were both expecting over 1"... Working on adjusting mine - knew something was up after had s small amount of rain last night and it reported zero...