I recently purchased a Canon EOS RP to replace my Canon Rebel T3i. I just tried to use my Neewer NW670 TTL flash with the EOS RP and it does not fire.
To be honest it has been a long time since I used the flash with my Rebel but my recollection is there wasn't any trick to get it to work. Also, I have a Canon Speedlite 320 with a "faulty" battery door but if I hold the battery door "just right" that flash works with the EOS RP without issue.
I don't have the manual for the Neewer flash any more and so far I have not been able to find it online.
Does anyone know where I can find the manual or have any tips for getting this to work? It's not critical because I rarely shoot flash photography but I'm going through my equipment to see what to keep and what to possibly sell.
I did a little quick search and didn't see any mention of compatibility with any Canon R series cameras. I too would have thought that it might work but wouldn't be surprised if it only fired in manual mode or only at full power. I'm not familiar with Neewer equipment, but have you tried contacting them? If this is an older model flash they may offer a software upgrade to make it work with some later camera models.
And I'm sure this is a typo but in one of their Amazon adds they do offer a 1% satisfaction guarantee!