User is able to select and enter time against the disabled client which was associated with bucket method project. Let’s assume that you have following clients associated with Project A which is bucket method,

Client 1
Client 2
Client 3

Disable Client 1 and it gets removed from the client list associated with Project A however, it allows users to selects Client 1 on timesheet and also allows to enter time against Project A. When you disable one of the clients associated in a bucket method project, it should not allow user to enter time against the project when he selects the disabled client.

Switch to the new smart interface with Standard 2.0 timesheet format, as this behavior has been fixed. The old Standard timesheet format won't efficiently update with this new functionality.