clan points

What do you mean by losing CP? There is no way that you can lose clan points. If you don't know 1 CP = 500 XP and CP get capped at 10 CP = 5.000 XP. Just make sure that you are in a clan and you don't leave the clan until you make sure that everything is fine. If you are still having the same issue you should report it with clarifying proofs via support ticket.

If you are talking about Clan Ranking then it is normal to lose points. If any clan gets more points then you clan your clan rank will get lower. If you also lose clan members you also lose clan points.