There's an updated Sold Secure list at https://www.soldsecure.com/Leisure.htm

The OnGuard U-locks (including the one I've been using for about a year) are no longer on the list, not even as bronze (it was silver when I bought it - I'm not in a particularly high-risk area).

Does anybody know what the story is here? (failed newer tests? not submitted? list omission? no longer available in UK?)

"Sold Secure‘s only source of income is from the fees it levies to undertake its work."

Don't know for sure, but most likely On Guard didn't want to pay the fees.