Since 1.5 upgrade Dropbox won't authorise

Hi,
I’ve been running WPB2D for months with no issue until I upgraded to 1.5. The upgrade went fine but it asked me to reauthorise with dropbox. I’ve tried to do so but the Dropbox site shows ‘The request to link the app is invalid’.
Then back on my site it shows ‘There was an error authorizing the plugin with your dropbox account. Please try again’.
I’ve tried on different machines and with different browsers, being logged into Dropbox and not an continue to get the same responses.
Am I doing something stupid or is there another issue here?
Thanks.
Chris Ellis, https://www.dual-ring.net

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