System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce RTX 2080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 442.92

Blender Version
Broken: version: 2.90.0 Alpha, branch: master, commit date: 2020-06-24 21:51, hash: rBec776f18ff70
Worked: (newest version of Blender that worked as expected)

Short description of error
In the Video Sequence Editor, there is a glitch with the blue needle. Whenever the animation is playing, it leaves a copy of itself.

Exact steps for others to reproduce the error

1. Open Video Editing Blender
2. Play the animation.

Notice a copy of the needle at the start

3. While playing the animation, pan the timeline view by Middle Mouse dragging.

Whenever the view is moved, the copy jumps to the current frame.

Thanks.