I've had wonderful luck with birds and cats.... don't take pics of people much, but tests for giggles have worked well. Being a landscape and wildlife photographer, it's been a fine tag-along.
I had a similar problem with my new R5 (coming over from Nikon and terrified).... There is a setting in orange tab #1, 3rd item down, 'Speed from metering/ISO Auto'. Set this to 'Retain speed after metering'. Voilá! Drove me crazy the first day out.
