I tried to reproduce it in our baselines example here: https://bryntum.com/examples/gantt/baselines/
I've added headerMenu : false into features config and reordered rows. All works well to me.
Could you please check again and let us know if any extra manipulations required to reproduce this?
I just tested this in Chrome, Safari, and Firefox on macOS and I was able to see the issue on all of them. The task can be picked up and dropped just fine but there is a console error and the orange line showing the drop location and the arrow showing the new parent are missing.
In chrome on the baselines demo the error I see is:
Uncaught TypeError: headerMenu[_0x1a0d(...)] is not a function