Cloth diaper irritation ?

My son is 10 months old, and we cloth diaper part time. I have noticed that whenever we use cloth diapers for an extended period of time without using any disposables, his belly button gets red on the inside.

We give him a bath every single night, we change him every 2-3 hours. He does occasionally pee through the diaper, but we usually wipe him off really good. I’m so confused! I hate using them for a long period of time because of this, but right now I’m home from work and would prefer to cloth diaper full time until I go back. What do you all think??