Why a page cannot be read · timeout
The page did not answer in time
Twelve seconds passed without a response. No verdict about the markup is possible, because no markup arrived.
The page did not answer in time.
§01 · what is actually happening
What is actually happening.
The request was made and nothing came back within the budget. This is a statement about the response, not about the page.
It can be transient. It can also be what a plain server request from a datacenter address consistently gets, when a browser from a residential one does not.
Nothing is recorded about your structured data, because none of it was seen.
§02 · what it costs
What it costs.
Directly, only that this read produced nothing. Worth repeating before drawing any conclusion from it.
Indirectly, it is worth knowing that most crawlers budget less time than twelve seconds. A page that takes that long here has already been abandoned by several of them.
§03 · what would change it
The fix.
The page did not answer within 12 seconds from a plain server request. Worth checking what your origin does under that condition, because a crawler with a shorter budget than ours would have given up sooner.
Who does it. Whoever watches origin response times. Start by checking what the origin does for an uncached request with no browser headers.
Check your own site.
One request, one verdict, no account. If this is the finding you get back, the page above is the one that applies.
See what a machine seesThe other findings