Very strange. It turned out that after time (pretty long) EF records were exposed for user. After backfilling I couldn't see result, in spite of refreshing and several restart PI System Explorer.
That updating DB process propably was in some queue.
Were you recalculating several Event Frame analyses or one in particular? If one in particular what's it's configuration and what are the data references of the triggering attributes? How many Event Frames were created during the recalculation? What version of AF are you using?