AC single phase motor control with a TRIAC - failure to trigger
Is it firing all the time? or not at all?
Short out U3 output to test the triac for full turn on. 
Are you firing with a pulse or delayed DC after ZCS pulse.

To minimise noise pickup, keep gate connection length to a minimum.
Take the return directly to MT1 (or cathode). 
If hard wired, use twisted pair or shielded cable. 
Fit a resistor of 1kΩ or less between gate and MT1. 
Fit a bypass capacitor in conjunction with a series resistor to the gate.

If 60mA is the worst case trigger current at low voltage with R8=470 this would be a trigger voltage of 28V should fire in all 4 quadrants.