In the future, So people don't have to download the image you have attached, please use the Insert Photos icon found in the Tool Bar of the Post and Reply text entry dialog window as pictured below. If you can please Edit your post to remove the Attached screen shot and Include it in the body of the text of your post.
You do that by Clicking the "More..." link at the bottom of your post, Selecting "Edit Message" and then use the "Insert Photos" icon in the tool bar at the top of the Post/Reply/Edit dialog box. If you can't edit your post please include the screen shot you attached to a new reply to this conversation. The Insert Photos icon is this one in the Tool Bar.
Consider resetting the preference file. Resetting the preference file is Adobe speak for deleating the preference file and then letting Lightroom Classic to recreate it.
The preference file can get corrupted, resulting in odd behavior. Some people have a knee jerk reaction in thinking they need to uninstall then reinstall Lightroom Classic, maybe that could be called for, but it would be better to first reset the preference file.
Be aware that resetting the preference file will result in Lightroom Classic creating a new catalog instead if opening your previously opened catalog (normally) so make sure you know where your catalog is.
Be aware the resetting the preference file will revert some settings in Preferences to defaults. So be aware of what you have changed, so that you can put those back the way you want them.
One thing to check: Go to your system preferences -> Security and Privacy -> Privacy tab. Scroll down on the left until you see "Files and Folders" Look for Lightroom Classic and make sure it has all the access to Removable Volumes and all the other categories.