Reporting: Not able to choose or create calc fields which are non-indexed

Reporting: Not able to choose or create calc fields which are non-indexed

If you are not able to create any calculated fields or use some of your fields in your report to filter it is because of the Data source that was selected is indexed.

Go to Advanced Tab, 

Report Performance >>  Optimized for Performance - Un-check the checkbox so that it allows you to use non-indexed fields on your report for filtering or create calculated fields

Remember that this could impact the performance of the report.