White series switch causing lights to blink when using dumb switch in 4-way mode

I have set up my white series switch in 3 way with a dumb switch mode and dimmer mode using a neutral.

When I control the circuit from with white series switch everything works fine. However when i change the position of the dumb switch (either on or off) and then the lights blink. Doesn’t matter if I turn the circuit on from the dumb or the white series switch. Then once I change the position of the dumb switch back. No issues again.

Any help here would be appreciated!

Thanks