Git Repository Network Graph commits out of order

Hi I use GitLab for 2 years already. One motnth ago I discovered weird situation on Graph of my project. (I use tortoise git on Windows) Example: There are 2 branches "develop" and his child "front" I made commit of my develop branch on local, then made pull from front to develop on local, after that i used "sync" to push changes to remote develop branch.

After that I see something like that

Lines going out of the graph field When I try to merge branch front to develop on GitLab page there is no commits to merge. When my friend make pull from remote/front to local/front then graph starts looking fine.

Why this happening ? I was using the same procedure many many times and everything Was allright. During last month every time I try but I have the same situation.

Can anyone help me to solve this ? Is this a bug or maybe I am doing something wrong?