Why does my contributed amount never increase?

Yep, they never had anything about it in the FAQ.

I created and completed a giveaway and the winner has marked it as received, but my contributor value isn't rising. Is there something wrong?

No, absolutely not. There're three reasons this might be happening. The first is simply solved by waiting. There is a delay of up to twenty minutes before your value changes and it will update shortly. The second is that single entry giveaways do not count towards your contribution value. Because they only got one entry, they are not considered as a raffle, but rather a direct gift. The other is due to having too many bundle games given away. Your contributor value will be locked until you submit further giveaways that are not from bundles and will continue to rise gradually until the full value has been reached. For more information on how values are calculated when bundle games are involved, please check this thread.

What does the asterisk (*) mean beside a game on the Create a Giveaway list?

An asterisk next to a game title on the Create a Giveaway list indicates that the game is included in the bundle list and thus you might not receive full contribution value for it. For more information please check this thread.

"I created and completed a giveaway and the winner has marked it as received, but my contributor value isn't rising. Is there something wrong?
No, absolutely not. There're three reasons this might be happening. The first is simply solved by waiting. There is a delay of up to twenty minutes before your value changes and it will update shortly. The second is that single entry giveaways do not count towards your contribution value. Because they only got one entry, they are not considered as a raffle, but rather a direct gift. The other is due to having too many bundle games given away. Your contributor value will be locked until you submit further giveaways that are not from bundles and will continue to rise gradually until the full value has been reached. For more information on how values are calculated when bundle games are involved, please check this thread."

I'll give you one shot where I pulled that paragraph from.

Edit: Well done community. Well done. Beat me too it :D