I lost a recent auction because despite having checked that I wished  to receive bid notifications I never got any so I didn't know that I had been outbid.

Lytala, you have Auction notification turned off in your account settings. Please turn it on if you wish to receive this type of notifications,

I just turned it back on but that's strange because I could have sworn that that it was on and that I recieved notifications from other auctions between now and when I last changed any settings.