Make sure auto launch is on. And set your crossover point higher, say 90%.

The 2019 SL is a heavy boat and you probably need to dump the extra weight when running a big crew. My 2018 SL 400 would run huge groups of people with 500 lb lead and full bag of fuel no problem. My 2019 MUST be heavier because the same lead with no gas in tanks has a harder time getting and holding surf speeds.

I’m working through the same issue you’re describing. I’m still learning the new boat and will check back to see if you find something that works.