User has set the Global Settings rule Skip time evaluation to allow billable time entries on projects even after they have reached the contract amount. However, when user checks the Global Settings rule Mark projects completed when billed 100%, the projects are marked completed when they reach the contract amount and you can no longer enter time on them.
This is the expected behavior in Core as Skip time evaluation (and its corresponding project-level rule) only comes into play if you are allowed to make time entries in the first place. Check the Core Help for details. So any rule that prevents time entries on a project will always supersede Skip time evaluation. This is the case with Mark projects completed when billed 100%, which marks the project status as completed when the contract amount is reached and prevents you from making any new time and expense entries on that project. If you want to continue entering time and expenses on the project after the contract amount is reached, you should uncheck this rule. Check the Core Help for details on Completed project status.