AFCI breakers in a Main Panel installed and tripping immediately with neutral pigtail connected
You need to move the neutrals for those circuits onto the breaker neutral lugs
Many AFCI breakers, yours included, have a ground-fault trip in them, set at around 30mA, in order to catch arcs and other firestartingly hazardous leakages to ground.  As a result, these AFCIs not only need their neutral pigtails connected to the neutral bus, they need the circuit neutrals connected to their neutral lugs, or else they will remind you of that requirement by instatripping on startup due to what appears to be an absolutely colossal ground fault (all the current going out through the breaker, yet none of it returning via the breaker neutral path).  (This is also required if you ever want to install a GFCI or DFCI breaker into your panel, by the way.)