EOS M100 AF Assist light not working

[ButtonPresser]

I had wondered why the camera was struggling to focus in low-light conditions until I realised that the AF Assist light is apparently not coming on when I half-press (or full-press) the shutter release. This happens whether in Intelligent Auto or Program mode, and I have checked that the camera is definitely set to one-shot. I have also checked that the AF Assist beam is set to ON in the third page of the settings.

Is there any other way in which the assist beam could have been disabled?

How unreliable are the assist beams - is it a known fault for them to fail?

The camera produces excellent results in settings with decent light levels - it is just in low-light conditions it just doesn' even attempt to focus.

[ButtonPresser · Accepted solution]

Probably scratch that last post! I seem to have fixed the problem by going to the Custom Function menu and clearing all custom functions, even though none were apparently set (all at "0"). Having said that the Custom Function I page is greyed out, whereas the Custom Function II page is available. It may be that there was a setting in C.Fn.I which I could not see for some reason.

One other thing to note is that recently I updated the firmware to v 1.1.0 which may have caused the glitch. I cannot say for certain as I don't absolutely know that the assist beam was working correctly before the upgrade.