I've had problems with block filling on my side. I've investigated the problem and created a fix. I saw that someone else (issue #425 ) had the same problem as me and with my version it replaces the blocks well.
Instead of using a try-catch, section.getCompound() can be switched to section.getCompoundTag(), which doesn't throw an exception but returns null if the requested CompoundTag doesn't exist.
I've had problems with block filling on my side. I've investigated the problem and created a fix. I saw that someone else (issue #425 ) had the same problem as me and with my version it replaces the blocks well.