We find the Event Income Detail report to be useful. But the Actions menu won't let me export this report into a CSV file for some reason. How can that be enabled?
Reports that provide a simple table are more amenable to export as CSV. The Event Income Detail has different sections to it which does not fit well for a CSV format - what column headings would you use?
Whether a report offers a CSV export option depends on the settings in the code. The Event Income Detail report is provided by
CRM/Report/Form/Event/Income.php You will see a line there saying
$this->_csvSupported = FALSE;
If you were to change that to
TRUE then the export option would be shown, but the rest of the report does not handle producing a CSV so that's not useful! ... unless you use that as the starting point to customise it to produce the output you want.
FWIW, pasting into a spreadsheet works pretty well: run the report, highlight the section of the report that you want, copy then paste into a blank LibreOffice spreadsheet, and you often end up with something usable. That might work with Excel too.
This feature is not available for Event Income Detail report but CiviCRM is an open source project so you would need to programmatically add this new feature.