[Venutius]

If a participant copies and pastes text from lets say a post and inserts it into a forum topic, while editing it all looks good, but once the topic is posted, then the formatting text is displayed as text.

Is this normal behaviour or is it a sign of another conflict?

[Stephen Edgar]

That should work fine, could be a plugin conflict, also could be an issue with “HTML entities” for example apostrophes ' and different language locales can use unicode syntax to save e.g. & # 0 3 9 ; (Edited to add a whitespace between each character so it displays correctly)