Unmount disk failed

I have an external harddrive that I use with Time Machine on my laptop. The situation is a bit clunky and I have to eject it in order to use my laptop as a laptop, but it has worked, until now. I thought there was an issue with the drive. I couldn't eject it anymore. No matter what I did it just would not eject. Even trying to use diskutil CLI, I could not unmount the disk. Google searches and trying different commands or using the disk utility application did nothing until I found an obscure stack exchange where someone else was having the same problem years ago and killing iTerm fixed the problem. So I killed hyper and was immediately able to eject the external drive. I thought maybe this was a fluke, so I tried again. If hyper is running, I cannot eject the disk. If I kill the hyper process, ejecting works as expected.

Reproduce the problem with Hyper running and an external Time Machine drive attached. Compare ejecting through the diskutil CLI and Disk Utility application, then verify whether terminating the Hyper process is the condition that restores unmounting. Done means the drive can be ejected while Hyper remains running, or the blocking behavior is clearly identified.