Unable to unmount external hard drive

My external hard drive has been having trouble unmounting so I tried to do this from the terminal and got the following error message: "failed to unmount: dissented by PID=230 (/usr/libexec/ApplicationFirewall/socketfilterfw)"

If I look in the activity monitor I can't find PID 230 and honestly I wouldn't know what to do with it if I did find it. I'm not sure what to try next so any help would be very much appreciated!

It's probably also worth mentioning that I have an anaconda environment on the external drive and the unmount problem seems to happen when I've been using the Spyder IDE.

Many thanks!