Fujifilm X-E4 RAW files crashing Capture One

I recently bought the X-E4 and always shoot in RAW. I edit in Capture One and the program keeps crashing and I’m stumped as to how to remedy the situation.

I previously shot RAW with the Fujifilm X-T10, using Capture One 12 with no problems.

I had to upgrade to Capture One 21 this spring in order to be able to edit the new X-E4 RAW files.

My system:

iMac 21.5”, Retina 4k, Late 2015.

macOS Mojave version 10.14.3.

3.1 GHz Intel Core i5.

16gb 1867 MHz DDR3 RAM memory.

Graphics Intel Iris Pro Graphics 6200 1536 MB

My usual workflow is to have the original RAW files in folders on an external non-SSD drive as well as the Capture One catalog on the same drive. Connected by USB 3.0

When I successfully open a catalog, everything is slow. When I start to edit, do anything with image files, the spinning lines twirl and I cross my fingers the process finishes and I can continue editing. Inevitably, the circle lines freeze, the slider lines lock up and the program freezes.

Using higher ISO files (800+), doing filter type of edits like clarity, de-haze, sharpening, luminance seems to be definite culprits on freezing.

Exporting files also freezes the program and my computer, definitely if the file is a higher ISO. For exporting, I usually get the window that pops up, Events. It will give the detail of: Could not process file. Description: There was an error during the processing of the output file. Code: 1.

The first freeze usually results in Capture One quitting. The second and successive freezes lock the computer and I have to restart the computer.

Upon restart, many times Capture One will open to the moment it froze, on a particular file and freeze again. An infinity loop. I have to quickly try and highlight another file, edit offline, some sort of band aid to get the catalog to stay open.

Whatever file froze Capture One, it is forever corrupted. Forget about any sort of edit, recovery, moving on. I can never export the file. If I am lucky, I can limp along on other files.

I upgraded to Capture One 21 14.3.1.10. No difference. I just upgraded to Capture One 14.4.0.135. No difference.

I tested a catalog and files directly on the iMac hard drive, to rule out the external drive and cabling. No difference.

Help!  Thanks!