Bizarre Google Analytics Phenomenon on My Site

Over the past 3-weeks, a website of mine is reporting very strange analytics data - but only for half the day.

The "Right Now" could be 5, but the number of people active on pages is 15-20.

Now the 15-20 is actually the correct number. Each day when I review the daily figures, for instance, the same normal number of users visiting per day reaches the site as it should. So there could be up to 20 people on Top Active Pages, yet only a third or so are stated as Right Now.

But at exactly 2.50pm, that's when Active Users drops by 50%, sometimes 70% compared to the number of people on Top Active Pages. This lasts for about 12 hours, and then things return to normal - where Active Users matches the number of people on Top Active Pages.

I checked my other 4 websites and they are working perfectly normal. They don't display this unusual anomaly.

This is the only one that is recently experiencing this issue, and it's very frustrating not being able to work out what is happening.

Surprise, surprise - it's happened again today!

I've attached a screenshot to illustrate what is going on. You can clearly see how the number of people listed as Right Now does not match the actual number of people on right now for Top Active Pages. The Top Active Pages is right, so why is Right Now not matching the data - and for only specific times of the day?

Why 2.49pm for 12 hours?

It's bizarre!

Any assistance with this is much appreciated.

As this is part of my business, I'm concerned about any suspicious activity.