I've always run sintered F&R on both bikes and never had an issue, even in the wet.
I buy these:https://www.amazon.co.uk/gp/product/B00 ... UTF8&psc=1
Are your pads getting contaminated at all? Maybe a teenie weenie leak or something around the caliper?
Its going to be something simple I hope, I've got race matrix in the front and semi metallic in the rear as I had a spare pack of these.
Have you tried swapping pads front to back?