When a new event with file attachment is created, the file is not saved on Google side (they don't support it) and is not even preserved locally. It was suggested to store the file on GDrive and just store the link (could be possible through customProperty) Reproducible: Always
This bug has only been reported for versions older than KDEPIM 4.14 (at most akonadi-1.3). Can anyone tell if this bug still present? If noone confirms this bug for a recent version of akonadi (part of KDE Applications 15.08 or later), it gets closed in about three months.
Just as announced in my last comment, I close this bug. If you encounter it again in a recent version (at least 5.0 aka 15.08), please open a new one unless it already exists. Thank you for all your input.