Disk space gone after failed Android build?

After a failed android build from Mac, I find 20gb of disk space gone. Nothing in the build folder! I cleared out some junk and uninstalled the android SDK stuff, but I am still some 13GB short of where I was before I began. SSHD being space-at-a-premium, I would like to reclaim this disk space but not sure where to look. Any ideas?

My UE4 directory only has 8gb of stuff.

What takes space is are object files (unlinked binery files), they getter in Intermidiate directory. But don’t delete it yet, if compiler finds a object file to a code file and don’t see code file modified it skips it and goes to next one, so free up space and resume compileing. Object files stays after compilation, main reason why is that with those object files you only need to compile modified files and do the linking, it shorts the build time if you devloping.

Sometimes there object files becames incompatible to eachother when you modify it, which causes linking errors which sometimes can cause random crashes, in that case you are forced to rebuild.