In answer to your questions...
- yes, twitter button works fine when Auto Post is disabled
- there's no html in title, the code I use with the Auto Post Plugin is
[category case=upper] : [title case=words]
[category case=upper] section enables the twitter button to work. Adding the category to the title seems to be what causes the twitter button to fail
- this occurs on every post. There are no exceptions
- the issue does not occur on the home/category pages. It only occurs on the single pages.
I believe the Auto Post Plugin does work on the first post, I don't think this is related.
Strangely, the twitter button DOES WORK, when the email share button is also activated. However, the email button then doesn't work, and spews out similar code to when the twitter button fails. Also, when the post is then shared via twitter, the link it gives it not as clean as the link it gives when Auto Post Plugin is not adding the category name to the title
I believe the solution will lie in amending the way the Twitter button grabs the title of the post.
I have left the fault on my site for you to see
Thanks so much for your help, it's much appreciated