I have been trying to complete this. I have carefully completed all the steps as stated. The response is still "Step not yet complete. Ensure that you are following all the instructions for posting to a Chatter group." I have not left anything undone. Please help out.
Hi Alison - All looks OK in the screenshot. I am sensing there is a white space in your post to Support group. Please check if there is any and also add the URL on the next line (after hitting Enter on your keyboard). Steps below. Let me know if this helps
1.) Copy "Hi Support people! Here is some quick training on how to use the @mention feature, to bring another user or even an entire group into a Chatter conversation"
2.) Ensure there are no white spaces
3.) Hit Enter
4.) Paste the URL
5.) Try verifying the challengeO.k., just for my international friends (if you post for example german text, that is layed out in the trailhead module, only the english text works!!!):
1. In the sales group past following:
Welcome to the All Sales group, which replaces the All Sales email list.
2. In the support group post the following:
Welcome to the All Support group, which replaces the All Support email list.
3. In the support group post a second post:
Hi Support people! Here is some quick training on how to use the @mention feature, to bring another user or even an entire group into a Chatter conversation
https://resourceful-badger-dxhul0-dev-ed.lightning.force.com/HelpAndTrainingDoor?version=2&resource=https%3A%2F%2Fhelp.salesforce.com%2FarticleView%3Fid%3Dcollab_add_mentioning_people.htm
The link might change, to get the link, follow the trailheads module instructions.
Thank you all a lot. Took some time, but I got it completed.
Best Regards
Andreas@Isabel Maria Graciano: I was facing same issue, make sure you enter the link immedieatly after text in All Suport group, once fixed my issue was resolved.
Hi Support people! Here is some quick training on how to use the @mention feature, to bring another user or even an entire group into a Chatter conversation https://help.salesforce.com/articleView?id=collab_add_mentioning_people.htm&type=5***There are two separate messages you need to post to the Support group:***
1) Welcome to the All Support group, which replaces the All Support email list.
2) Hi Support people! Here is some quick training on how to use the @mention feature, to bring another user or even an entire group into a Chatter conversation.
https://help.salesforce.com/articleView?id=collab_add_mentioning_people.htm&type=5
Be sure you're adding BOTH messages to the Support group, as well as making sure there are no white spaces in the message when you are copying the messages into the box.
This tripped me up as well. Thanks for the clarity. Basically, if you copy and paste the text directly from Trailhead, then it will have hard returns which are NOT what the Verify Step is looking for. 
Hi Sujay - thanks that was the issue ...I copy pasted text in and so it was adding in the gaps ...I typed manually and made sure no unnecessary gaps and all good !! hoorah - badge now completed ...thanks so much for taking time to look and respond to my query. How to complete 'Create Chatter Groups' unit in 'Prepare Your Salesforce Org for Users' - I have tried in two different playgrounds and triple checked that I have followed all the instructions exactly but verification keeps failing so I am stuck ! I have alredy done all the steps that is on this post, but with no sucess. Someone could helpe me? Hi Sujay,
Thanks that was so silly. I removed the white space and it worked. It is very frustrating when spaces bother you from getting your badge at last step.
thankyou for the helpHi - error is ' Step not yet complete in My Trailhead Playground 1
Ensure that you are following all the instructions for posting to a Chatter group.'
Same error in playground 2Hello,
I have tried in two different playgrounds and triple checked that I have followed all the instructions exactly but verification keeps failing so I am stuck ! I am able to add suzuki funmiko but not able to add aaron and the rest of the module require the users data in order to complete
