A user reported this issue to me - I am not able to replicate it on my computer so I am attaching a video of her screen. When she adjusts the width of the collection organization tree panel, it suddenly jumps to the bottom of the screen. Video shows our local instance of ASpace but she tried the same test in the sandbox and had the same issue.
Lenovo laptop, Firefox Quantum 64.0. She did not experience the same problem when using Chrome on the same computer. I cannot replicate the problem with Firefox on my Dell computer.