I have a user who is seeing the "lock" anytime they are updating dates in a project they own. I've looked in help but not seeing anything on that topic. Any assistance would be helpful.
i think that what you are referring to is the indicator that the system is recalculating all the dates based on changes you've made to the dates. Is it a large project? I think if they refresh the screen, it may go away.
Those dates represent fixed (locked) dates.
If using the fixed date both the start and end date would show a lock.
While Must Start date will lock the start date and leave the end date fluid. Inversely Must End date will lock the end date.
Hope that helps.