I see 3 issues:
1- Interface shows none on the Mount points knowns, this is not normal as it shows USB on the Online drive table
2 -MountTo is empty in your known mount points , it should be filed with the full path to your
3- you should have a Modify action in the mount points known table before the remove, but this might be linked to the problem in 1.
hit the remove link
then redo the procedure:
1- hit add on the first table
2- fill the Mount To filed with /home/e-smith/files/ibays/myibay/files/MYFOLDER
3- save
wait for drive to mount or hit mountto action to mount it
add some file
come back to manager, hit unmount
remove drive
check the content of your folder MYFOLDER that should be empty
if the issue persist about the interface = none, you will need to fill a bug in bugs.contribs.org and provide more logs in order to investigate, sometime some usb drive are not beahing the way they are intended to. Some seagate are known to be bad example.