We have the same issue - it has happened 3 times now. 2019 Fi23 with the 450. We will be surfing fine, and then at some point the wave goes to garbage and the boat won’t go over 9. We can drop the stinger plate to 80 and maybe get up to 10. But can’t reach the 11.2 on the pro surf canned profile. Happened on both regular and goofy. Reaching out to the dealer, but the only fix we found (and VERY frustrating) is to dump the ram fill, completely shut off the power, and then start over again.