Git - commit button doesn't work


I have atom installed on two Mac. On one Mac git works smoothly, on the other mac I can fetch, pull, I can stage, but I can’t commit. I fill in a commit message and the commit button is active, but nothing happens on pushing the button. No error, no message. I can commit on command line or Source tree and atom shows the new commit immediately (there is a .git folder inside the project, no problem with source tree), but the commit button doesn’t work.
I deleted the .atom-Folder, the atom application and the other folders in Application support and reinstalled atom, but no success.
What can I do?