Gangmenu roster and onion tablet roster don't match

There is a discrepancy between the number of members I can see in the gang menu/the onion tablet. The people I can't see on the onion tablet are unable to see any /gangmenu info; they just get the option to create a gang even though they're already part of ours. I can see 20 people in the gangmenu, but only 17 on the tablet.