Symptom
When you push your repository from PowerBuilder IDE to your Git server for the first time after you do the Add to Source Control, it may fail when the size of your source code is large and/or your network is slow.
Resolution
After you do the Add to Source Control, the local repository is created and everything is ready to be uploaded to your Git server. At this time, you can try a third-party tool like TortoiseGit to push your code to your Git server. After the issue push, the successive pushes will be small, so you should be able to push from PowerBuilder IDE after that.