I have posted elsewhere regarding cache updating - previously I have "Fetched" in WMT and submitted and within minutes the cache is updated... this has now stopped working... I have a niche news website with new content daily...

Assuming you don't have hidden content, which is the discussion on another thread, even google's own responses to this seems ambiguous. Google: Tabbed, onLoad, or Hidden Content No Longer Indexed] [webmasterworld.com]

The cached date is separate of crawling & indexing, so I wouldn't use that as a metric.Cached date different from crawl date [twitter.com]

Worth noting that in the current (Nov 2014) Updates and SERPs thread [webmasterworld.com...] there have been numerous posts recently about caches not updating.

Here's the earliest and most detailed observation I've found, posted by Itanium on November 19....

Google is really going crazy this past couple of weeks. It seems they have released multiple updates since the official Penguin roll out, but almost every time there's a rollback to the dataset of October 21st. Every time that happens, the cache of one of the pages on my site is set back to that date. I have updated the page multiple times, sent it to google using WMT and the new version got indexed multiple times, but every time, it just sets back to the old cached version at some point. Happend again the past few days.

I've posted on another thread recently as well that caches are independent of indexing, but, from posted reports here, this seems to be something different... as though Google is reverting to an old data set (something that generally precedes a large update).

Again, though, it's usually the data itself, not the cache, that provides these signals. Conceivably, if this is an update beginning to happen, it could be an update in how Google caches pages.

Robert, do you remember there being such a long gap between cache updates previously though? I am also quite interested by the separation there is between the sites that have been updated and the ones that have not, I.e what is the reason for the division? Looking at news sites, they all seem to be immune so I am presuming it has something to do with content change frequency. All high traffic, governmental, high authority and news sites seem to have had a change while the small/medium type sites have not. Can't see any other pattern really. Will have a closer look at this when I get the chance.

I think after cache update, result position can very fluctuate.

There is some talk of a bird trying to fly

Did Google Release Penguin 3.1 On Thanksgiving?
https://www.seroundtable.com/google-penguin-3-1-thanksgiving-19504.html [seroundtable.com]

[edited by: aakk9999 at 7:04 pm (utc) on Nov 29, 2014]
[edit reason] Made link clickable [/edit]

Notice penguin movement over the holiday (U.S.) which coincided with a cached date update...