Possible cause

WARNING: This page is about a different car, the 2017 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.

Connector terminal disconnection, poor contact, damage, deformation, corrosion
Open circuit in wiring harness between front body control module (FBCM) and connector C-03
Open circuit in wiring harness between connector C-03 and connector C-12
Open circuit in wiring harness between connector C-12 and connector C-12
Open circuit in wiring harness between connector C-12 and connector C-33
Connector C-03 malfunction
Connector C-12 malfunction
Connector C-33 malfunction
CAN circuit in front body control module (FBCM) malfunction