Note: this issue may be automatically fixed once we solve: #12199 but not necessarily, so I'm opening a separate issue here.

To reproduce:

• Open Behavior > Events
• Below the "Event Categories" report, click "Export"
• in the popover, Click "Expand subtables"
• Select format TSV or CSV

Got a file that only lists (as the "Label" column) the "Event categories"
It doesn't have what we expected, which are the sub-tables.

Note:

• This issue was also reported for a Custom Report. Exporting custom reports to CSV basically miss out on all the sub-dimension columns.
• as a possible solution, maybe we make "Expand subtables" the same behavior as "Flatten" for exported reports, where each dimension would be its own column: this should be addressed in Keep flattened columns as extra columns #12199

For example an expected, instead an output that contains also all keywords, for each search engine, for example like this:

Label (Event Category) | Event Action | Visits | Actions | Maximum actions in one visit | Total time spent by visitors (in seconds) | Bounces
-- | -- | -- | -- | -- | --
Cat1 | - | 14766 | 804764 | 27899 | 5104896 | 10005
Cat1 | event action 1 | 100 | 804764 | 27899 | 5104896 | 10005
Cat1 | event action 2 | 80 | 804764 | 27899 | 5104896 | 10005
Cat2 | - | 325 | 70127 | 28705 | 270106 | 201
Cat2 | event action 1 | 50 | 70127 | 28705 | 270106 | 201
Cat2 | event action 2 | 70 | 70127 | 28705 | 270106 | 201