Hello @Dafftt
In short: in Athletica, Form is your start-of-day freshness and Fatigue is your end-of-day load. When you did your session on Saturday, your fatigue jumps. But your Form for Saturday was already set that morning (after midnight). The drop in Form shows up on Sunday (the first moment you’d actualyl feel the impact of your session starting the day.
The one day offset is expected. Fatigue= after training, Form = before training. Rest days then let fatigue decay and Form rebound.
If you like the nerdy bits, we use modified Banister model (check for a link in your Help&education in your settings) to track short-term vs. long-term load. Also, keeping RPE and well-being logs tight helps the model mirror how you feel day to day.
I think @Andrea could shed some light here, and there was a great thread on this earlier
MJ