Canon Speedlight 430EX III-RT flash: cannot get it to fire on optical slave mode - Please help

[Casey415]

I have a new 430EX III-RT speedlight which works fine on my Canon EOS M50 camera when placed on the hotshoe.

But I cannot get the flash to fire on optical slave mode off camera. I have referred to Page 78 of the flash pdf manual over and over again, but the flash simply won't fire on optical slave mode. I have watched many YouTube videos about this and did many Google searches on this but cannot resolve this issue.

I have the pop-up flash enabled on my Canon M50 camera. When the pop-up flash fires, the 430EX III-RT flash does not fire even when set to optical slave mode.

What am I doing wrong? Or do I have a defective flash? Thanks!

[diverhank]

As far as I know, the M50 cannot control as a master without a controller such as the ST-E2.  BTW, Optical slave mode symbol is the lightning bolt, not the "antenna" symbol which is for Radio mode.