It might be helpful to for you to detail what you have tried, so that we aren't suggesting that you try things that you have already done.
I created a new catalog named Tweets. These are for images I've tagged with keywords, told the story of the image in the Description field, and are ready to go to my Zenfolio site at both HD and 4K. I also use these for social media posts, not just Twitter, although that's how it started. This catalog should contain the images in two folders; one is "tweets 1920x1080" and the other is "tweets 1080 square" which are inside the "tweets & presos" folder. When I first created the new catalog, I selected both folders in Folders to Scan, but that didn't work, so I selected each folder individually, which didn't work, either.
It would also be helpful to see a screenshot of your "Scan to catalog" window, perhaps with the output that you see when you attempt to initiate the scan.
I've attached it. It returns the Scan Complete result almost instantaneously. But the path in Folders to Scan is correct. Since the screenshot of the Scan to Catalog window doesn't show it all, here it is:
/Users/stevemouzon/Library/CloudStorage/Dropbox-StudioSky/Steve Mouzon/Mouzon current files/Correspondence - Dropbox/tweets & presos/tweets 1920x1080
Is there anything about this path that would cause a problem?
And lastly, please send us your log file. This may contain filenames and file paths and other information specific to you, so if you prefer not to post it publicly on this forum, please send it to support@camerabits.com
You can find your log file by going to the 'Help' menu and choosing "Reveal support Data", this will bring you to a ZIP file called PM_log.zip.
Attached.