I have run into the same exact problem. Ported over all my adwords keywords, set to broad match mostly, and got them all approved. Set max bids on all to $0.07.
Yet only some of them are showing. One example is one of our primary keywords. On the search results only 6 ads are showing, so there is definitely room for ours to show, yet it doesn't. This is a super-high relevant keyword for our site, and even the useless AdCenter tech support agrees with me that it is a super high relevant keyword. Yet they can't seem to explain to me why it isn't showing... they just keep suggesting I raise my bid to a very high amount and try for the #1 slot.