Source IP persistency breaks when disabling and re-enabling the load balancing virtual server which has Source IP persistency configured.
In the persistency table, we can see only one backend server is mapped to the Source Client. However, when you run the command "show ns connection table", we can see the connections from same Client goes to different backend servers.This is a known issue (BUG0686409). To resolve this issue, upgrade to NetScaler 11.1 build 54.14 or later versions.