Home never went to probate mortgage company won't accept payments

[Rich Hupper]

Hello BP 

I have the following scenario I am trying to wrap my head around right now:

Neil owned a home and has it mortgaged with Citi Mortgage. Neil has owned it for 50 years and allowed his daughter Anne to live there for the past 20 years with her family. 

Neil became sick in 2013 and died in 2014. He died testate ( with a will ) with his daughter Anne named as the devisee for the property she currently resides.

Before Neil died Anne was added to the deed. Also before Neil died "seterus inc" either bought the mortgage or is now the loan servicing company ( Anne was unclear during our conversation ).

After Neil died Anne tried to make payments for the mortgage but Seterus told her they cannot accept her payments because she is not the person named on the mortgage. 

Lo and behold, she has not been able to make mortgage payments since october 2014.

This scenario raises many questions for me

1) When a property is mortgaged and the mortgagor dies but the real property  is bequeathed to a devisee; what happens to the due on sale clause found in most mortgages?

2) Is this title issue the reason properties go to probate?

3) What would be her best course of action here, especially since she does not want to lose her home.

4) What type of attorney should I refer her to?