Am I able to download a previous version of PH+, just want to test, because I think this has been happening since I did the last update on the 19th March
As RogerB said, prior builds are available on the announcements forum, but we haven't seen any uptick in support tickets that indicate that the new build would be having this issue.
As Kirk suggested, its pretty odd for the log file to say that Photo Mechanic is setting its memory cache to 16 GB when your settings indicate something else.
Something else I am noticing about your preferences is that the disk cache is not being cleared on quit. So if Photo Mechanic is caching out these low-res previews, it will just use the cached version of these images if they are accessed in the next 100 days unless the disk cache fills up first, so quitting or rebooting the application would not do anything here.
Please try this:
Set your Memory Cache to anything other than 13 or 50% (10% is probably fine, longterm, so I would suggest that).
Click both "Empty now" buttons in the caching preferences window. Click OK, and then Quit Photo Mechanic.
Start Photo Mechanic again, and open a few Contact Sheets. If the issue persists, please generate a new log file and send it to support@camerabits.com, and a member of the Technical Support team (probably me) will be in touch.