Moving HEIC content in Final Cut Pro X

I'm having trouble moving events containing HEIC content between libraries in Final Cut Pro X. This is effecting both the copy and move event commands between libraries as well as dragging between events on the different libraries. All other content within the events copy without issue if HEIC content is deselected manually. Trying to move an event with HEIC content within just fails on start. I've checked that permissions for both libraries are correct. Moving the files between events on the same library work.

When copying a project with HEIC content within, the HEIC is copied automatically without issue.

Final Cut Pro X 10.4.3 on macOS High Sierra 10.13.6 on MacBook Pro 15in Mid-2017.

Source library is on the internal SSD (Macintosh HD) with an APFS file system while the target library is on a external storage device configured with HFS+ (Mac OS Extended) file system.