Ah you must be talking about the one of the preffered server bonus. They swap the servers list around so your server might no longer be on the preferred server list.

If you would kindly tell me your server and I can confirm it for you

Please Help.
Thanks !
I didn't find the right solution from the internet.
References:
-https://steamcommunity.com/app/39210/discussions/0/3223871682607473722/
- Animated Demonstration Video