Lightroom Classic: Moving Images on Disk no longer works properly

I process my photos in Lightroom Classic CC on my Macbook Pro (running 10.13.6), then move the folders of raw files to my external RAID array *from within Lightroom* to maintain the links so LR knows where everything is. This used to work perfectly: LR would create a folder of the same name on the external drive, copy all the raw files to it (while deleting them from the laptop), then delete the folder from my laptop. 

Now this process breaks down after the files are moved. The empty folder remains on my laptop, the process "Moving Folder" remains in progress, and the empty folder still shows on my laptop hard drive with a question mark over it. Everything else worked - the files are on the external drive in the proper folder and linked to LR - but it doesn't finish cleaning up. Any ideas?