Unable to open USB files from LibreOffice debian file dialog

I am using the Ubuntu version of LibreOffice on Zorin Os.
When I open the file dialog to open or save a file there is no option to open from any USB stick that is connected to the PC.
I can open the files if I use Nautilus file manager and once opened they can be saved.
I know with the Windows version I was able to choose either the Windows file manager or the Libreoffice open/save dialog
Is it possible to use Nautilus from within LibreOffice?

The Open file dialog has a left pane with the list of known mounted devices (below the “favourite” list). Click first on one of the devices to display its contents in the main box.

You may have ticked Use LibreOffice dialogs in Open/Save dialogs section of Tools>Options>LibreOffice>General.

Remark: “the Ubuntu version of LO on Zorin OS” gives us no information about LO release number. Moreover, you don’t mention Zorin nor Ubuntu version. Prefer to quote what is reported by Help>About LO.

When you opened a file from usb, use SaveAs instead of Save, but not to save, but to check wich location is offered. If it is the same folder from where the file was opened, you may try to get to this path also with the usual File>open.
Today drives are often “mounted” below /media but you may also look at /mnt or /dev

Which Ubuntu packages? If you are using the Ubuntu Snap version, access to reading and writing from USB is prohibited by default by the Snap jail settings. You would need to find the command to free yourself from this jail for the LibreOffice application by whatever mechanism ZorinOS makes available. In the Ubuntu App store, there is a separate GUI toggle for managing the per-app exceptions, I have no idea whether ZorinOS has something similar.

Thank you, the ‘Use LibreOffice dialogs’ was ticked. All good now.