P: Import stuck on checking free space on disk

I've emailed you with instructions

OK, I have the log file -- let me know how to get it to you?

Ah, got it. Will do!

After you are stuck on the Calculating for a while.

Will do, but I'm not clear about your instructions:

As soon as you see the message appear

For LrDesktop

What message is that? Where would I look for that message?

I'd like to collect a diagnostic log from you.

Restart Lightroom. 

As soon as you see the message appear

For LrDesktop

• Go to Preferences
• Account Section
• Hold down the [Opt/Alt] key to make [Diagnostic Log] button appear

When you have the log message me here for instructions.

Hi @8510810,

I appreciate your help getting this solved! Per your questions, here's the info on the external hard drive:

• Total Space:  4 TB
• Total Free Space:  1.66 TB
• Format: APFS
• The drive is connected via USB3 cable directly to USB port on iMac (no hub)

Note that the external drive already contains copies of all LR originals (approx. 1.7 TB).

Other technical info:

• iMac (Retina 5K, 27-inch, Late 2014)
• 32 GB RAM
• System drive:  500 GB SSD (75 GB free)
• Mac OS Big Sur 11.2
• Lightroom CC 4.1
• My library contains just over 205,000 items

Drive details from system report:

Bucket:
  Free: 1.66 TB (1,662,273,335,296 bytes)
  Capacity: 4 TB (4,000,577,273,856 bytes)
  Mount Point: /Volumes/Bucket
  File System: APFS
  Writable: Yes
  Ignore Ownership: Yes
  BSD Name: disk7s1
  Volume UUID: 1FF82DC7-9D62-4481-ABEE-41FF24EE4B57
      Physical Drive:
      Device Name: USB
      Media Name: AppleAPFSMedia
      Protocol: USB
      Internal: No
      Partition Map Type: Unknown

Can you give me additional details on the EHD?
Total Space:

Total Free Space:

Format: 
How does it connect (USB port? Hub? Other)

Thanks @8510810 --

Thank you for your advice. In brief, after I reset the LR preferences, the problem was gone; I imported several folders of photos, and import worked like a dream. 

But then as soon as I restored my "Storage location for originals" preference back to my external USB drive, the Checking free space on disk issue once again stopped any further imports.

Here are a few additional pieces of information that might point toward the cause of the problem:

After I reset LR's preferences and imports were working again, I noticed in Preferences / Local Storage that the "Available space on Logoplex" showed 62 GB available ("Logoplex" is my internal system drive). "Required Space" showed 25GB, I think, and "Photo Cache" was 23 GB. 

But then when I restored "Storage location for originals" preference to my external USB drive and imports stopped working, I saw that, "Available space on Logoplex" just shows "CALCULATING..." forever, while "Required Space" and "Photo Cache" show 0. Note that this is what I've been seeing in my Preferences for the past few days of problems, and it seems like it could be related to the "Checking for free space" message I get when trying to import. 

In case its relevant, note that I have not yet check the box for "Store a copy of all originals at the specified location," although that is what I will eventually need to do. The box had previously been checked, and there are currently nearly 200,000 items / 2TB in that folder. 

Finally, you asked:

Have you restarted your computer?

Yes, many times, and I've been closing background stuff (i.e. DropBox etc.) and all other apps before running LR.

So it seems like the problem is in some way related to storing my original files on an external drive. 

Have you restarted your computer?

Have you reset preferences?

Reset Procedure:

1. Close Lightroom.

2. Hold down [Alt/Opt]+[Shift] while restarting Lightroom.

3. Overwrite the Preferences when prompted by the dialog.

4. Close Lightroom.

5. Restart Lightroom.