Moving a photo never finishes (but files are moved on disk)

So this is a weird one, wondering if you guys can help out. This just started today, no big changes in the computer or Lightroom. I just came back from vacation and have been importing to Lightroom mobile and letting them all sync up to Creative Cloud. Now I'm home I have the files in the Lightroom Mobile folder on my Lightroom Classic app. All good.

I've been trying to move the files, just one or two at a time, and what's happening is the file will move on disk (ie: in the finder the file is moved from Lightroom Mobile/2019/2019-01-30 to Photo Library/2019/Vacation-All), but the photo showing in the folder in the Lightroom library doesn't.

[ Just because it's confusing, I'm using the term "file" to represent the "physical" file on disk, ie: /photo library/2019/vacation/image1234.dng and "display image" to represent the object that's in the Lightroom library that's a representation of the "physical" file. When I talk about the folder on disk I mean I the filesystem (/home/user/pictures/photography/photo library/2019/blah/blah/image123.dng) and the library folder is the folder that's displayed under "folders" in the lighroom library. ]

So:

• The "moving..." text in the top left where it indicates what is going on never goes away (ie: it'll be "moving" forever until I hit the 'x' to cancel it)
• The file on the disk moves to the new folder
• Lightroom puts a new display image in the destination folder in the library
• Lightroom never removes the original display image from the original folder in the library

The end result of this is I have

• The physical file is in the destination folder on the disk
• A display image in the destination library folder
• A display image in the original library folder with a "!" showing the source file is missing (which is correct because it's been moved to the destination folder on the disk)

I have no idea WTF is going on, and this doesn't seem to be happening all the time. I just moved some files from the Lightroom mobile folder to a folder called 'test' in the Lightroom UI just fine. Then I tried to move a single file from a folder under my photo library folder to another and it did the 'moving...' thing.

Here's an image of what I'm seeing. I had just dragged IMG_5575 from the "Kenya and ..." Library folder to the "London Stopover" Library folder.

I thought it might have been some sort of permission issue, but the file permissions all look fine, and I have tried deleting the previews and smart previews, in case it's an issue moving the preview file somehow, but no luck

Note this is moving one or two images at a time, not a mass move, and origin and destination are all on the same disk (4t fusion drive in an iMac) and all software and OS is up to date.