Thanks for reaching out. We are sorry for the trouble with Lightroom. We are here to help.
Could you please share the version of Lightroom from Help > About Lightroom? Are you exporting directly to the external drive? Have you tried exporting to a location on the internal drive?
In Adobe Lightroom, please share the screenshot of the following options as shown below from Preferences.
- Create a test album in Lightroom.
- Right-click on the album and save the album locally
- Export the album to an internal storage location.
If changing the destination of the export changes the outcome, you can further do some trials with the external drive and USB ports. Check the antivirus/software program on the computer to find if Lightroom or its components are not blocked or interrupted while accessing the internet and the local storage.
Let us know if this helps,