Llian wrote:
...am I missing something here?
Possibly. Teamwork management structure?
You might have reserved Teamwork editing rights to the Schedule itself, but (as ARCHICAD User Guide explains in detail) Schedule is a live, two-directional connection to any project element and since you had not reserved the right to edit that specific element — you can't enter notes.
Basically, if you want to add notes to a custom field you've created in any Teamwork Schedule you would have to reserve items you are editing, not the schedule, i.e. in your case — individual sanitary equipment objects.