Selective credit giving
Some people are very good at selectively giving credits in such a way that maintains or increases their own status within a group while, at the same time, preventing those they (subconsciously) see as threats from gaining status.
This type of manipulation works especially well in a close-knit group of people, where those who are perceptive enough to notice such manipulation also fear speaking out will ruin the group. An alternative to mitigate this type of manipulation is to be the one who gives proper credits in a highly visible way, and do it consistently. If all fails, perhaps avoid engaging to protect your own sanity.