On occasions, pressing VO+Space on an external keyboard will trigger the Context Menu rather than activate the item VoiceOver focus is on
On occasions, when using an external keyboard, you will find that when you press on Control+Option+SpaceBar the Context menu will be triggered rather than the item VoiceOver focus is on at the time being activated.
This doesn't happen often, but frequently enough to be an irritation and to indicate that there is an underlying issue.
It also doesn't appear to be widespread in terms of where it can be encountered, but has been seen on Home screen icons, in the mail app, and in RSS and Twitter apps.
There appears to be no pattern to the behaviour... it just randomly happens.
Steps to reproduce
As this appears to be a random issue, there is no way to consistently or reliably reproduce the behaviour.
However, a common example has been in the native Mail app on an iPad.
If you place VoiceOver focus on to an email in the list of emails displayed in the left column, and then press Control+Option+SpaceBar you may find that the Context menu is triggered rather than the email message being displayed in the right column of the app.