Thanks for writing in, we’ll be happy to help out here.
So, unfortunately, there isn’t a way to explicitly block a user from only selecting their user in the
person field. If they have permission to change the
person field (which is what tracks who the time log is for), then technically they can change that value to something else.
Having said that, when you create a new time log, it will always default to value to the user who is logged in. This should help ensure that time logs do not get created as blank.
May I enquire as to your use case here, are you trying to avoid users incorrectly setting the wrong user, or do you have another kind of workflow where people log time for other users perhaps?
If you have any further questions don’t hesitate to give us a shout.