Had poorly placed dermal filler in 2016, 2 years on now had hyaluronidase to dissolve them but filler won't dissolve.

I had 1.5ml of Juvederm in May 2016 followed by 1ml of either Teosyal or Restalayne kiss in September 2016. The injector placed the filler poorly instead of going back I decided to wait for my body to dissolve the filler. There are 2 visible lines of filler under my top lip. I have had 2 appts now with a qualified nurse who used lidocaine mixed with hyaluronidase. I am currently 36 post 2nd treatment. Could it be scar tissue from the poorly placed fillers? Why won't it dissolve?