I still believe this is a problem of the Speedlights (EL-1 or the 600EX series), and I do not believe the ST-E3-RT is the issue. The reason I say this is because I connected two (2) of the EL-1 Speedlights and one (1) 600EX speedlight to my trigger (...
Canon fails to even acknowledge the issues, why should they care, they have the money already from the purchased hardware. Then you will find out you need third party Godox to make it workable.
I would read up on all of the comments about the Canon flashes losing the LINK between the remote and the flash. While I have had no problems with the remote, the flash will lose the link if you have any WiFi hot spots in the area. Buyer beware, I ha...