This is also broken in 702, previously working in earlier versions of 7.x
Thank you, Katie. Good to know it's not just us it's affecting.
Investigating further, I've noticed another place this happens. When adding a status update, if you reference other Jive content by typing the @ symbol the issue seems to be compounded, as seen here:
It also happens when the content is a Discussion item, but of course the root of the problem is still related to Status Updates so I would guess it's related to that component.
Just to note that this has been logged now as a bug in the system and is being investigated by the Jive engineering team. The bug reference is JIVE-53054.