How to fix code fold?

Question

Sublime Text

Hello, maybe someone knows. Everything worked fine, the 2nd level shortcut in one group stopped folding. The mouse folds unfolds the norms.

if (a==1) {
   if (b==2) {
      if (c==3) {
      }
   }
}

.
1 is ok, 3 is ok. Above this group is normal. Below this group is fine. There are no visual differences from normal groups. How to find such a glitch?