I had this issue with the LMP1 at Sepang -. a couple of flatspots is certainly enough to destroy a tyre with no collisions or excessive wear. The workaround was to reduce braking power and shift the balance to the rear and just be really gentle, even avoiding kerbs. I understand those cars are on the old tyres so maybe that is why.
I wish every .ini parameters would be exposed in the UI when logical (perhaps, under an "advanced" tab)