There are a few Preferences that we would like to know how you have them set.
First, is "Enable RAW Rendering" enabled in the Render Cache section of Preferences?
No.
Next, in the Caching section of Preferences what values do you have set for "Disk Cache", "Reserve at least", and the "Memory Cache" slider?
10,000
10,000
1638 MB
In the same Preference pane, is the Cache located anywhere other than the default location of: ~/Library/Caches/Photo Mechanic?
No
Thank you for your prompt response !