External hard drive folders missing

I have been having this issue off and on for the past couple of years.  It currently has gotten worse.  Folders will randomly have (?) and be greyed out as will some (but not all) images inside the folder, although they were there previously and haven't been moved.  Sometimes they will come back on their own but sometimes the only thing that fixes them is to quit lightroom and reopen.  It's becoming a huge annoyance.  Find missing folder/image doesn't work.  When I try that, I select the missing folder (which is right where is is supposed to be), nothing happens in lightroom.  Folder remains missing.  Oddly, even though a folder is missing, usually some of the images inside that folder won't be missing.  Not sure how lightroom knows were the images inside a missing folder are, but not the folder.  Seems like it's a software issue.   I have not had any success figuring out what the problem is.  This happens on multiple external drives.

What do you mean by "Lightroom CC"? There is no software by that name. Do you use Lightroom Classic (LrC icon) or Lightroom (Lr icon)? What is the version NUMBER?

But yes, agreeing with @Rob_Cullen , you need to explain in a lot more detail what you mean.

Assuming you mean LrC:

Folders do not "show up" in the Folder Panel. They appear when photos exist in the catalog database in that folder. A common mistake made by users is that the folders are missing because when you imported the photos, you accidentally used "Copy" instead of "Add", and so LrC will not show the folder you think the photos are in, LrC will show the folder where the photos were copied into. Please search the LrC catalog following all four of these steps:

1. In the Lightroom Classic Library Module, on the left, under Catalog, click on All Photographs
2. Turn off all filters (Ctrl-L once or twice)
3. Turn off all stacking (Photo->Stacking->Expand All Stacks)
4. Search for at least one of these photos by file name using the Lightroom Classic Filter Bar

What is meant by "not showing up"? Do you mean they have a [?] on the folder? Are they 'greyed out'? Do they simply not show whatsoever? Are sub-folders expanded out from a 'parent' folder?

How are you sure you are in the "right catalog"? Do you see the "right" Catalog name? Do you have more than one catalog?

Is it possible the drive is "Sleeping"?  Check it is showing a green light in the Folder panel.

Could it have a faulty usb cable? A little movement may break the cable or usb plug (even the usb socket).

Explain "Randomly". Is it while you are using LrC, or on occassions when you restart and re-open LrC?