SharePoint Online LIst View Item not Showing

There could be a few reasons why your "Group By" filter is not showing any items in the SharePoint Online list view. Here are some things you can try to troubleshoot the issue:

1. Check if the column you are trying to group by has any blank or null values. If yes, then try to filter out those items and see if the group by filter works.

2. Check if the "Group By" column is present in the list view fields. If it is not, add it to the list view fields and try to apply the "Group By" filter again.

3. Check if the "Group By" column is a calculated column. If it is, then SharePoint Online may not be able to group by the calculated column. In this case, you can try creating a new column with the same formula as the calculated column and use it for the "Group By" filter.

4. If none of the above solutions work, then it may be due to the large number of list items in the view. SharePoint Online has a limit on the number of items it can group by in a single view. In this case, you can try creating a new view with a filter that limits the number of items in the view and then apply the "Group By" filter.

I hope these suggestions help you resolve the issue with your SharePoint Online list view.