Could not save file because write access was not granted

I am working in Photoshop through Lightroom by - photo > edit in > Photoshop CC 2017 > edit original

Photoshop opens automatically and I can do my edits, everything is fine up to now.

After I do all my edits in Photoshop and hit save, instead of saving and automatically returning to Lightroom with the new edited file,

the message "Could not save file because write access was not granted" comes up.

(I will have to "save as" to desktop, copy, replace the file, and then select "import setting from disk" in Lightroom)

Finder is in list view, the file is unselected so it's not the Preview's issue.

The file is not opened by any other application.

I have full access to the location of the file: create, rename, save over, replace, delete.

The only reason I can think of is because Lightroom is using the file so Photoshop can't save over it.

But that is nonsense. I'm editing the file in Photoshop through Lightroom, they should be working together...

I'm running Mac OS High Sierra 10.13

Lightroom cc 2017

Photoshop cc 2017

Can someone please help me?

Thank you,

Cindy