Can’t get groups created from MS Teams from Graph endpoint /beta/me/joinedGroups

With MS Graph API you may use /beta/me/joinedGroups endpoint for getting list of groups where current user is a member. With the same endpoint you may also get isFavorite attribute for the group which shows whether or not user added group to favorites. However this endpoint has own issues: recently we found that it doesn’t return groups which were created from MS Teams: when you create new Team there also related Group is created. It is possible to get details of this group using basic groups endpoint

https://graph.microsoft.com/v1.0/groups/{id}

But if you will try to get list of user’s groups via beta endpoint such groups created from MS Teams won’t be returned:

https://graph.microsoft.com/beta/me/joinedgroups/?$select=id,isfavorite,displayName&$top=200

One possible explanation could be that internally /me/joinedgroups end point is routed to Outlook services which is not integrated with Teams well enough yet: when I tried to add createdDateTime attribute to the REST url (this attribute is returned for groups from basic endpoint - see above)

https://graph.microsoft.com/beta/me/joinedgroups/?$select=id,isfavorite,displayName,createdDateTime &$top=200

it returned error saying that returned entities have Microsoft.OutlookServices.Group type:

May be this is a bug or such functionality is not implemented in beta endpoint yet. For now I asked this question in StackOverflow – hope that somebody from MS Graph product team will answer it.