Most pocket nappies have a stay dry lining that is made out of polyester.
Occasionally this lining can start to repel moisture and cause leaks, instead of wicking it away.

Repelling could be due to:
1. Detergent residues not rinsed out of nappy could clog the pores in the lining.
2. Use of fabric softener would greatly clog these same pores and cause massive repelling.

To fix this, do a 'strip washing' on the affected nappies. Please refer to the instructions under 'Use & Care'