I was surprised to find that the Google Patent sidebar was not rendering for the US application tagged in this question. It occurred to me that it might be due to multiple patent numbers being tagged in the question. I removed all but the US application patent tag, and the sidebar rendered fine.
It turns out that if some other patent number tag (e.g., WIPO, EU, CN, CA) appears before the US application or grant patent tag, the sidebar will not render. If the US application or grant patent number tag appears first, the sidebar does render.
This might be a “status by design” question, but I would like to know what the intended behavior is in this case. Frankly, it would make sense if only the first tag were used, since multiple sidebars are not rendered. However, maybe this should be the first patent number tag for which a summary can be generated.
Update 1: It appears that the problem has returned. The sidebar is no longer being displayed.
Update 2: The same problem occurs on a question tagged with more than one US patent number.