MS Project Master file won’t allow Duration/Deadline edits

Hi Tom, what was the process you used to migrate your schedules from the POL cloud environment to the Project Server On Prem environment? We've completed a bunch of these migrations and in our experience there's an important 'order of operations' for how schedules need to move from POL to PS SE, so that things like enterprise fields, resource assignments, etc. map and function properly.  Based upon your input we'll provide some guidance.  For instance, when you moved the individual sub-projects, did you create a new project in PS SE and copy the schedule into that new project, like you noted you did with the Master?

Also for any calculated fields you are using, are they Enterprise Custom Fields or the out of the box roll up fields (like work, duration, etc.), and how did you migrate those between environments?

Master projects can be tricky to work with, esp during a migration effort.  Breaking your individual schedules down and migrating and validating those individually, after you've updated your PS SE configuration to match what's in POL, is a good starting point. From there, you may need to re-build the master, as in Project a master is really a separate project schedule that includes a set of sub-schedules (which you clearly already know from your note above).  Esp. if your links go across projects, those 'pointers' are stored in the POL database attached to specific task UID. If those UIDs change or are published as new UIDs in the PS SE system, it's highly possible you'd break those links when you do the migration of each schedule, and esp within the master, which is just rolling those projects up.