BO Authentication problem for users synchronize from SAP

My BO server have license for 15 users.

I have 32 users assigned the role for synchronize to SAP BO, 11 users account are disabled. So, there are 23 active user assigned to the role for sync in SAP.

I recent found that some user missing in BO in sometime. Some of the user in BO overwrote often.

I also found that some of locked user/disabled user synchronize to BO, and some active user are missing.

Do anyone have suggestion of this problems?