USB FDD of the host machine cannot be used

[leisure person]

The USB FDD on the host machine cannot be used as a non-USB FDD on the guest machine.
When I try to connect the USB FDD of the host machine as a non-USB FDD from the "Device" menu while the guest machine is running, there is no response.
When I try to connect from the guest machine's "Settings" screen, the host machine's USB FDD seems to be connected to the guest machine as a non-USB FDD, but it does not work properly, such as not being able to save files.
Also, if the OS of the guest machine is DOS, an error will occur in EMM386 by connecting or disconnecting the FDD while the guest machine is running.
From the above, I am having trouble using the physical FDD on the guest machine. For convenience, I want to use the USB FDD of the host machine as a non-USB on the guest machine.
Do any of you know a solution?

[leisure person]

VirtualBox, please solve the problem that virtual FDs including host USB-connected FDDs cannot be used properly in 7.0.
Upgrading to the latest version 7.0.12 didn't solve the problem, so I downgraded to the previous version 6.1.48 and it was resolved.
If there's no problem with 6.1 but not with 7.0, there must be something strange going on with 7.0. Please solve it quickly.

[scottgus1]

If you can demonstrate that 6.1 works but 7.0 does not, and can provide a VM vbox.log under 6.1 with the drive working, and another log under 7.0 with the drive not working, then a Bugtracker ticket with the logs zipped and attached to the ticket may help the devs.

Please note that pictures don't translate, so typing out on text what the picture says would be helpful.

[mpack]

There were no removable floppy drives (as opposed to disks) in DOS days, so I'd say that the EMM386 fault may be a red herring and should be ignored on "one topic one problem" grounds anyway.