In Dolphin, there was a bug with GCZ compression for 10 days or so that made all newly created GCZ files corrupt. It was fixed in Dolphin in 5.0-1991 (9 days ago), but I don't know what that corresponds to for Ishiiruka. The fix prevents corrupt files from being created, but existing corrupt files will still be corrupt.
There isn't really a way to automatically restore your corrupt GCZ files to correct files (though since only a part of the GC/Wii header is missing, it is possible to at least recover them manually). It's probably easier to re-convert them from ISO (or whatever other format you used).
There isn't really a way to automatically restore your corrupt GCZ files to correct files (though since only a part of the GC/Wii header is missing, it is possible to at least recover them manually). It's probably easier to re-convert them from ISO (or whatever other format you used).