Whilst my work has been getting a little excited about the summer party, I was having a look around the hashtag feature in Yammer and what we can do with it.
One of the cool things Yammer does when you use a hashtag, it creates a group which gives it a group ID (so cool) so you can then setup a feed on a page that draws certain hastags from yammer.
As the page it has created is for a group, you’re given the option to change the name of the group. As a hashtag cannot have spaces, it would seem like this would be a good way to make some hashtags make more sense, especially if you’re using acronyms.
The unfortunate truth is, if you change the name of a group created by a hashtag it then breaks all of the uses of the hashtag in posts. Posts just show “#undefined” where your hashtag once was.
If you have changed the title of one of these groups, to get your hashtags working again you just need to change the group title back to what it was and the hashtags in posts will work again.