FAQ Project Plan 365
FAQCategory: Calendar
I am accessing some task to change predecessors, but they do not auotmatically move. It keeps the start date and duration as priority, rather then logic links I am giving with predecessors. For example one task is Finish to finish with the previous one with a lag of 7 days (so it should finish 7 days later). It does not move it!
Question Link

Yes, the reported issues is not a issue, also in MSP when a task have progress(%>0 ) the start dates is not changed when user try to change predecessors or change project start date or any other actions.
"If a task has any actuals applied, such as an actual start date or a percentage of work completed, the task can't be rescheduled any earlier than the date when the task actually began. If no progress is entered and the task has an inflexible constraint, the constraint can take precedence over task dependencies."
Solution: Please remove % complete values then try again to change predecessors value ​