Shelly 3EM negative consumption values

Welcome to the forum!

To your issue:

(a) negative power values without a power generator (e.g. photovoltaic plant) are obviously provoked by incorrect mounted current clamps. They have to be turned in the opposite direction.

(b) low power factors indicate a wrong connection of the voltage terminals: phase VA must coincide with the wire where current clamp A is mounted! Same for VB/clamp B and VC/clamp C.

Suppose, you’re suffering with both issues, (a) and (b).