Canon Speedlite 580 EXII will not fire on EOS R5

[CORNED1]

My flash won't fire when the shutter is activated in any mode. It DOES fire when I press the red button. I've also tried all the modes on the flash, I usually use ETTL.  Any suggestions?  Thanks in advance.

[Peter]

Mechanical shutter?

[CORNED1]

Nope! Electronic.

[Peter · Accepted solution]

Then change to mechanical.

[CORNED1]

My first cut at a reply disappeared after I clicked on Accept as Solution. Thank you! Switching to mechanical shutter fixed this as well as another "problem." My remote shutter release wouldn't work either. Thank you! Thank you! Thank you! Why in the world would a fully electronic digital camera not do everything when in electronic shutter mode?

[Peter]

Due to rolling shutter I suppose.

[Kerro]

1st curtain also works. Agreed that electronic will not fire flash. I also was surprised to find the 580ex-ii on my R5 will fire my Yongnuo YN460-ii flashes when in they are in slave mode. I have 2 of them.