Korganizer does not sync with google calendar

[ntmikey]

After adding new calendar of type "Google Calendars and Tasks" in Korganizer, everything is correctly pulled from the google calendar.

Afterwards, sync is working one way only. Appointments entered/modified in Korganizer show correctly in google calendar a few moments later, but data entered/modified in google calendar never show up in Korganizer.

Setting "Enable refresh interval" does not help.
Update calendar does not help.
Update calendar folder does not help.

I've first noticed this bug in 16.04, and it is still here in 17.04.

ProblemType: Bug
DistroRelease: Ubuntu 17.04
Package: korganizer 4:16.04.3-0ubuntu2
ProcVersionSignature: Ubuntu 4.10.0-26.30-generic 4.10.17
Uname: Linux 4.10.0-26-generic x86_64
ApportVersion: 2.20.4-0ubuntu4.4
Architecture: amd64
CurrentDesktop: KDE
Date: Thu Jul 13 08:38:39 2017
ExecutablePath: /usr/bin/korganizer
InstallationDate: Installed on 2016-02-15 (513 days ago)
InstallationMedia: Kubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
SourcePackage: kdepim
UpgradeStatus: Upgraded to zesty on 2017-07-12 (0 days ago)
XsessionErrors:
 (virt-manager:2542): Gtk-WARNING **: Theme parsing error: gtk.css:68:35: The style property GtkButton:child-displacement-x is deprecated and shouldn't be used anymore. It will be removed in a future version
 (virt-manager:2542): Gtk-WARNING **: Theme parsing error: gtk.css:69:35: The style property GtkButton:child-displacement-y is deprecated and shouldn't be used anymore. It will be removed in a future version
 (virt-manager:2542): Gtk-WARNING **: Theme parsing error: gtk.css:73:46: The style property GtkScrolledWindow:scrollbars-within-bevel is deprecated and shouldn't be used anymore. It will be removed in a future version