Do you always know what are you working on?
Team members should always know in what task they are working on and make sure Azure DevOps (was TFS) is up-to-date.
It’s natural that everyone spends some time on grooming, making decisions etc, so it’s not expected that all team members work 8 hours per day on tasks. However, ideally everyone should be doing as many hours as possible.
If they are doing something for the team that is not a team meeting or for a task assigned to them that will take more than 30 minutes, they should create a new task with an accurate original and remaining estimates. When helping somebody else with a task, the team member should create a new subtask to that task to cover their help.
To always know the task you are working on is very important for the Burndown accuracy and also make it easy to check what work has been done and what are the impediments.