I haa d a 500 MPA and FTP of 199W for an indoors ride (Tacx Neo), even coming down from a calculated max power recorded outdoors of 870w and an outdoors FTP of 210w. I could barely have the MPA go down to 330 after a very substantial and long effort. Today using a similar signature using a Quarq DZero power meter, I rode outdoors for a very prolonged time with the MPA stuck at the lowest limit (of 200w). For some reason (or many reasons unknown to me), I can put a lot more power outdoors than indoors, making the indoors signature useless on an outdoors ride and viceversa. Have you noticed this same pattern?
This often happens if you are using different power sources (Neo vs. Quarq). It can also happen if you’re not accustomed to riding indoors. Many individuals have poor heat dissipation and they struggle from too much heat retention, which will affect your ability to reach MPA. Other factors can also be involved. Many athletes can perform identically indoors and out.