We experienced the same issue. I'm not real sure why anyone would really want to share their profile if they are not going to gain anything from it (like being able to use other people's custom foods). My wife and I typically eat the same things so it would be very helpful to be able to actually do more than LOOK at her custom foods - I still have to enter the same info myself to add it to my log.
Come to think about it, it would be VERY nice to just have two searches - a built in food database search that we have now AND a custom food search that compiles all of the foods people have manually entered. That way, the food database would get big really quickly, but you can still have a separation between "trusted" source and a wiki-source, if you will, where you kinda need to verify the accuracy. But at least it would be there.
I just hate when we BOTH have to add the same custom foods and it seems like Fitday kind of tricked us into sharing our profiles by saying that you could share custom foods, but then you can't do anything but look. Seems like a stupid feature.