Hey Martin. Welcome!
Xert will estimate all three of your signature values to establish your entire power duration relationship. Ideally, the relationship between all three can be established from your historical data (usually requires a few breakthrough rides to provide the algorithm information on this relationship). If you just go with a single ramp test, that relationship isn’t established unfortunately since it’s a test protocol and not a natural expression of fatigue, recovery and attempts at different intensities that you’d see during a race, for example.
The signature could very well be right, but if your PP is good, you might want to examine the HIE value which is quite low for an athlete with TP over 300. Raising this value, will lower your TP to identify the single breakthrough at the end of the ramp test. Simple clicking the Extract button might work, or you might want to lower TP and increase HIE before clicking that button. If you’re stuck, reach out to support who can help with this.