Here, in una.io we have this bug fixed now. So in your site seems you need to check your Channels version (Studio->Apps market->Updates). If you see that it is available for update, then need to complete it.
My site is up to date and appears to be working fine right now. This is a screen shot of right now, when I click on #Channels within this post. #Hashtag works fine, so perhaps just an issue with that link.