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?
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.