[I couldn't find a bug report mentioning this issue – I can't really imagine that nobody else is bothered by this –, but I assume I might have my search terms wrong. :) So, in case the issue was indeed already reported before, please point me there, thank you!]

In our enterprise installation of Confluence, we encounter weird issues with the Task function. Certain users prepare pages with tasks beforehand, possibly using the @user-mention syntax in order to auto-complete the user's names, but remove the @user-mention so the users won't get notified before the page is completed and the tasks become valid. Later, when everything is set up, the @user-mention is added again.

This procedure seems to provoke cascading and/or even empty user-mentions through-out the task list, which cannot be removed or tidied up by a normal user using Confluence's rich-text editor. It tends to become manyfold worse if parts of the affected tasks are being copy-pasted to new tasks. Worst of all, the problem cannot even be "seen" in edit mode, it only becomes apparent as soon as the page is saved, see screenshots 1 (page view mode) and 2 (edit mode).

Another rather disrupting side effect is that in a user's profile's task list, the tasks inadvertently enclosed in user-mention snippets will always remain displayed in a single line rather than getting line-broken, so the task list can be so long that the page has to be scrolled horizontally in order to find out on which page the task is to be found (see screenshot 3) – apart from breaking the page layout, of course (see screenshot 4).

The obvious cause of the problem appear to be SPAN tags that are being inserted into the page for certain (maybe somewhat "unorthodox"?) actions – and remain there, even if empty. In some cases, I found cascaded SPANs like the one in screenshot 5 (HTML blob of task numbered with "08" in screenshot 1). This screenshot is from page view mode, but in edit mode, the page's source looks similar. However, as the cascaded SPANs are not visible in edit mode, there is no way for the user to "correct" the syntax. Well, except for editing the HTML source code directly while in edit mode.

Anyway, I don't think this should happen in the first place. In my opinion, multiple user-mention cascades should be filtered out to a valid syntax while editing or when saving the page.

I have no idea how the users actually ended up with such a corrupted task list on one of the affected pages. However, once you end up with a corrupted task list, in can only get worse, with no way from within the rich text editor to correct or even notice the issues. So, I could only guess what the users might have done "wrong" originally, but at least I could reproduce a garanteed way to mess up a task list, just for the sake of this argument. Steps to reproduce:

• Create a new task list from the macro
• Type "@" and select a username, nothing more, and save the page
• Re-enter edit-mode, and unlink the user's name. Now, from the end of the user's name, having the cursor blink right behind the last letter (move the cursor there with the cursor keys), continue typing out a task. Save the page. This should have you end up with the whole task enclosed in a @[user-mention] SPAN.
• Once here, whenever you copy-paste even a few words from this affected task to a new task, you will end up with more and more cascades.