Answer is almost certinly that you had a filter on - something like only showing profit/loss greater than 0.2 BTC.
When the user wins they only profit by 0.1 BTC or less so it doesn't show up - but when they lose they lose 1 BTC and yo usee it.
Same for the other guy below - except there he was betting at high odds so only his winning bets showed up not his losing ones.
Nothing strange is happening - just you're seeing only a small part of the results (due to a filter you set) and then mistakenly believing it's all the results.
Except the filter in the accounts tab is amount risked, not amount gained/lost. Unless you are talking about the chat room bets, in which case that does seem to be amount gained/lost and your post is correct.
Yeah, sorry guys - have win/loss filter 0.11, so win 0.1 isn't showing up. Fooled myself.