I have a goal completion when user visit the specific page. Also I'm sending event from this page to count how many times user visited this page during the session (and for some other info). Now I'm trying to make a custom report (flat table) that have info about: Session ID (custom dimension), Event Category (secondary dimension), Goal completion (metric) and Pages/Session metric. In this case I see that Goal completion is zero for every session although I see events from the page (and I know that goal was completed in every session cause it's testing site).
If I remove Event category from custom report then Goal completion equals 1 for each session (that is true info). And if I'm trying to use Event category in filter it is the same situation - I don't see Goal completed.
'Event Category' is a hit-level dimension, but other dimensions and metrics have session-level. It's invalid dimension-metric combination.
Try to use custom segment with conditions: include sessions where 'Event Category' = [your value].
Good explanation of scope in GA: https://www.bounteous.com/insights/2016/11/30/understanding-scope-google-analytics-reporting/