Empty report, but dataset is ok.

Hello, I have this issue where our custom dataset shows exactly what we need, but when creating chart and report it comes empty. 

Dataset is:

select distinct("user"), concat('/',split_part(url, '/',2), '/' ,split_part(url, '/',3), '/' ,split_part(url, '/',4))
from $log
where $filter and app = 'Google.Docs'
and ((url like '/spreadsheets/%') or (url like '/document/%')) and not (url like '%backgroundsync%')
group by concat, "user"

Can anyone help ? Probably this is a bug ?