Back pay itf

So I've filed my first itf in 2020, and have been fighting claims since. I recently got 90% with this last claim starting in February of this year. Reached out in regards to this since they said I got the 90% in March and have received nothing, and was told to wait but I will only get back pay for this claim not my original itf? If I've kept my claim status open the last five years continually should my backpack be my first itf or am I missing something?