I'm getting incorrect P&L data also, on the Betfair site.
The P&L on the Betfair individual market page is VERY different from what is shown for the same market on the Betting History page. No idea which one is accurate.
Hm. Very interesting....
Now getMarketProfitAndLoss returns ZERO sometimes only. How can API be so glitch? We're working with money, not digits on the screen.
It has been fine since - but it looks like a few others perhaps saw something around the same time as there is a thread about the site at roughly the same time I saw it hang. Hopefully it was just a blip with my own connection.