Same problem here. Please put some work in this functionality...
Tried searching for a group "Volvo C30" on mobile phone. No results.
Tried creating the group on mobile phone. Group already exists.
Tried searching for the group on www.waze.com/dashboard/groups
website. No results.
Tried creating the group on website. Group created.
Now I have the group as my main group on the website but it doesn't show on my mobile phone. I also can't find it on my mobile device... Booo