help: external hard drives show 0 items until reboot

Missed the report entirely. It's usually at the bottom of the reply so by habit that's where I looked.

First there is no reason to ever install or run any 3rd party "cleaning", "optimizing", "speed-up", anti-virus or security apps on your Mac.  This user tip describes what you need to know and do to protect your Mac: Effective defenses against malware and other threats - Apple Community   

With that in mind uninstall Sophos according to the developer instructions. You can check to see if you've removed all of the supporting files by downloading and running Find Any File to search for any files with the application's name  and the developer's name in the file name.  For example for Sophos software you'd do the following search: 

1 - Name contains sops

Any files that are found can be dragged from the search results window to the Desktop or Trash bin in the Dock for deletion.

FAF can search areas that Spotlight can't like invisible folders, system folders and packages.  

Also that applies to PACE. It's not necessary.

Also uninstall Memory Free. It only interferes with the macOX's built in memory management and offers no benefit.

The same goes for Time Machine Scheduler (let TM do its thing as it was designed) and MacFuse. Neither is needed nor offers any benefit. Time Machine Scheduler has been crashing a number of times

If you're running the Seagate software to manage the external HDs you don't need it. The macOS does that very well. The Seagate software will only interfere with the macOS's operation.

Chrome is a known resource how and it is also reported as crashing quite a few times. If you don't like Safari try Firefox. It's more reliable and secure than Chrome.

It's also wise to reboot more frequently than every two days or longer. Rebooting clearers out temporary system, cache and swap files and will help with performance.

If the above doesn't fix the problem I'd remove all of the items in your System/Users & Groups/Login Items preference pane and then add them back one at a time while checking to see if the problem still exists or not.

The booting into Safe Mode is actually a fix attempt:

NOTE: Safe Mode boot can take up to 10 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

So boot into Safe Mode and then reboot normally. Run for a while to see if there's any improvement.

Begin by restarting in Safe Mode with all the external drives disconnected. Then re-start normally, introduce 1 drive at a time and see if it shows up. If it does then begin adding the other drives 1 by 1. If you do not have any luck please let us know and we will ask you to post an EtreCheck report so we can look for obvious issues.

By the way. I get you don't want to upgrade the OS, however please consider upgrading your legacy apps. The longer you wait the more difficult it will be to try to stay current. We see this issue often and it is never fun for users that try to have their systems live in the past.

Okay, please do the following:

Please navigate to the Mac App Store or navigate to www.Etrecheck.com and download the free version of EtreCheck. Once you have you downloaded the app and installed it, please run the report and save it. This report will help us get a good idea what has been installed on your system and help us be able to diagnose what may be wrong.

When you have your report, you can attach it when you reply to this message and we can then review it and help you determine what is needed to get your system running well again.

For instructions on how to download your EtreCheck report and attach it to your reply to this message please click https://discussions.apple.com/docs/DOC-250000211

Have you tried force quitting the Finder to see if that will show the items?

Copy the Etrecheck report

and paste it into your reply using the Additional Text button:

I noticed in the report that even with 32 GB of RAM you were still getting swap files. That indicates that you have a lot of apps running at the same time. Limiting that number will help with performance.

Another app that is not necessary is PACE. There is no reason to ever install or run any 3rd party "cleaning", "optimizing", "speed-up", anti-virus or security apps on your Mac.  This user tip describes what you need to know and do to protect your Mac: Effective defenses against malware and other threats - Apple Community   

Do you have external HDs that are not formatted for Macs or PCs, i.e. FAT 32 or ExFAT? Otherwise what are you using MacFUSE form. It's not needed, nor its any Seagate software, for managing normally formatted hard drives for Macs. In fact they will hinder performance.

OT is correct, your system will boot into Safe Mode but you need to be patient while it's starting up.

I would recommend against upgrading Mac OS until you resolve the problem though, if the Safe Mode start does not take care of it the problem the it has not been addressed. An upgrade of Mac OS could make finding the real cause even more difficult.

It will help. :)