Success!!
But I'm not sure why......!!
Checked and found I was actually sending data to wunderground as well, and that has a complete history so points towards a weatherlink issue.
Reset the data interval (properly this time, forgot the tick box previously), which cleared the history, and now seeing data both in weatherlink and wunderground.
Not sure why this would fix the weatherlink issue, or what it was, but presumably something to do with the 'stuck' barometer reading even though this was not 'stuck' on wunderground.
Also not sure why I cannot share with, or see, KomokaWeather Live even though I can see local stations - something to do with country maybe as I am in Scotland?
Anyway, thanks for your time and efforts, much appreciated!
John