I found that this was an issue with injesting files, when you do a compare of files, RAW, between an injested file and non-injested you would find a big difference, an exert is attached.
Updating the latest version fixed it for me, but my issue was that ALL images were not showing a thumbnail and I couldn't import them into LR.
What is most disconcerting for me is that there is NO reference to this in the Release notes with the latest version that fixes this issue.