In years past, we've seen a repeated problem in Moodle's forums that use groups:

1. Faculty create a forum, turn on groups, post to the forum asking students to reply, but they regularly miss clicking the collapsed "Advanced" tab, thus missing the "Post a copy to all groups" checkbox. 
2. The result: Students in groups cannot reply to the teacher's prompt
3. This is especially problematic in a Q&A forum where students are not allowed to post anything (reply or new post) when the teacher's post does not belong to their group

Video showing the issue, above, in 2 minutes: https://www.loom.com/share/7ce453599ef249399483afe18a335c36 

The Proposal:

• Make forums auto-sense if the forum is set to use groups
• If so, when a teacher role posts to such a forum, auto-prompt the teacher asking, "Would you like to post a copy to all groups"? Clicking Yes would send the forum post to each group. Clicking No would post one post to no groups.