Basically I have the same bug someone had a while ago:

https://jira.atlassian.com/browse/SRCTREEWIN-1781

Git can't add super long filenames and deletes them instead of adding.

This seems to be a serious bug, I just lost files, because every file above a certain name length Sourcetree "believes" it was deleted after you modified it and removes it after commit.

SUPER annoying

Steps:

• add a file with a super long filename which causes the bug, add via command line.
• modify file(s),
• add in Sourcetree and commit. it will get deleted/be shown as removed

I just modified files and as always Sourcetree wants me to add them:

Screenshot:

https://imgur.com/oglCXY2

Directly after adding the files, one gets removed from my workspace, only chance to get it back was the local history (thank god!)

Screenshot:

https://imgur.com/x9TdwJZ

My git version : 2.18.0.windows.1

Sourcetree : 2.6.10  

OS: Windows 10 Enterprise 64bit

I can add and commit the same files with git bash no problem, one change in these files and they are deleted after "git add ."