If you create an OU blog and set it to have a grouping (e.g. so that you can restrict it to a subset of students) but do not turn on group mode (because within that subset, you want it to just be a single blog for everyone), no posts are displayed.

This is because there is logic when it gets posts to apply restrictions based on grouping.

I propose to remove these restrictions altogether so that:

1) If you are viewing a specified group, you will always get that group [regardless of grouping or not]
2) If you are viewing all groups, you will always get all posts [even if they are in groups which are no longer in that grouping]

Note: #2 could apply, for example, if you remove a group from a grouping after people have made posts to the blog for that group. After this change, those posts will continue to appear in the 'all groups' view.