I placed about five or six - 6 second video clips into the timeline and sometimes when I try to slide one video clip over another video clip to create a transition the video clip will slide back to the way it was originally in the timeline and not overlap the other video clip on the timeline.
This also happened to me in version 18.09.
When I tried repeating this again today shortly after it happened earlier today the problem did not reoccur.
I just wanted to let you know that this has been happening.
As the instructions state in the thread for the beta report the issue in that thread. Don’t make a separate thread for issues with the beta.
That’s what this thread is for: V18.10 BETA program and download
What this sounds like is that you are not setting the clip down first. Sometimes you have to place the clip right against the other clip that you want to make the transition with and set it (meaning letting it go). Then you select the clip again and cross the clip with the other to create the transition.
This is currently by design and not a bug.