Same thing happened to me. This week I've had to do it over a few times because my skin also split in the middle and it f***ed up the progress. I was f***ing pissed. Now my middle area of my bottom lip is raw again where I had to remove the loose parts of the barrier. Luckily the left and right sides of my bottom lip are doing good so far after 3 days of application.
It's been 7 days since I applied the cream to my top lip and I don't know if that area is healed but the color seems to be normal like the rest of my top lip that's not affected.
The skin grows back really fast underneath the barrier. I said it only takes approximately 2 days to notice new skin if you keep the barrier on.
This was not an easy week for me, hopefully next week things will go more smoothly. I'm still hoping to get cured by the end of this month. I believe it's possible.