No, Problems don't go away on their own. Eventually one needs to locate and address the problem. ( I really don't have much hope for Tahoe 27 as it will effect some other areas that I have - will see )
Now. On to that Folder not opening. After I had deleted it and then reconstructed it ( only had about 4 files in it - it remains fine right now ) It occurred to me later I should have loaded it on a USB Flash Drive and see if my very old iMac would open it. But, too late as I had deleted it after hours of trying different methods of opening it.
Then, another Folder on the desktop refused to open today. So thinking now's the time to test a Folder ( not opening ) on my iMac. This Folder holds 41 video files at almost one GB. So I just dropped it on my Flash Drive and walked it over to my iMac. Yes, it worked on my iMac, who knew. It even opened in the Flash Drive. I then dropped it into my iMac desktop and it opened.
I found a file I did not create in that Folder - a Folder within the Folder labeled, A CacheSystem - which held only one video (23.4MB ). Don't know where it came from. I didn't create it or put anything in it, much less put a video in it. Last time I opened that Main Folder there were no other Folders in it. The video in that folder was similar to all the other videos in the Main Folder and one I had downloaded sometime earlier. So it should have been with the others.
I deleted that Folder ( A CacheSystem ) and then placed the Main Folder back on the Flash Drive. Walked it over to my Mac Mini, opened it on the Flash Drive to see if it might work - it did ( maybe should have tried it on the Flash Drive when it was still on Mac Mini before going to iMac ) - then loaded it on Mac Mini Desktop. File opened with no problems.
So was it the A CacheSystem folder that caused the problem ? - where did it come from ? Will other folders do the same later ? I have yet to delete any Cache folders. This is the second Folder that has had this problem of not opening.