I have a Modern library filtered and grouped view that displays "Show All" when the expanded group exceeds 30 items. Upon clicking "Show All" or the group heading itself to view all items in that group, it does not display any results, however it works perfectly in Classic experience.
The library has hundreds of document sets – one for each Job Request – so we have created a view that filters for Document Sets only and excludes several values of a Calculated Column (i.e. "Job Status" is not equal to...), then group by the items by the same calculated column ("Job Status").
The problem appears to be grouping using THIS calculated column (contains IF statements) – the same view works when I select any non-calculated column or another concatenated calculated column to group by. When I re-introduce this particular calculated column for grouping (even at a second level) it fails to display results again but again will do so correctly in the Classic Experience!
PS: Also, is there some way to configure for more than 30 items before "Show All" appears (PS: I have increased the collapsed number of groups to display value but this doesn't affect Modern "Show All".