Pretty much as the title says… what’s the fix?
Full disclosure, I weight doped recently as I intended on completing the Haute Route as a Z1/2 slow ride (but didn’t want it to take forever). I didn’t end up going more than 1km before I had to stop. I then changed my weight back. So… 97kg > 60kg > 97kg… could this be some sort of hangover from that?? Karma!! 
Appreciate any help you can offer 
I didn’t realise that people really did that… 
What’s your cadence? And are you on a hill?
I think I worked it out. I dropped my FTP recently. It was obviously too high because I was much fitter when it was last recorded.
According to that link, you stand up whenever you put out double your FTP. Which would have only been 3w/kg for where I had set it.
FTP auto updated at the end of that ride, so hoping my avatar will sit a bit more in the next ride! 