Just so happens that I e-filed a return similar to what you mentioned yesterday and it was accepted. Daughter claiming refund for mother who passed in 2020. She was not court appointed, or a certified representative but I hope this helps. 

Still complete Form 1310 (it asks if they are a personal representative and request you to attach the certificate)

Pt. I with box C checked, then check box C1 (you may check box A instead)

Pt II  checked she did have a Will "YES" box 1; box 2a & b checked NO; box 3 YES

E-file sailed right through.