This issue is reproduceable, I reproduced it. Right after a fresh install I could not enable Akonadi either.
I finally got it to enable but only after messing around with other settings like Kwallet, Online services, search, etc., and repeated attempts aka hitting apply more than once. Even now, if I disbale Akonadi again it can not be just re-enabled and often have to go inand out of Plasma settings re-applying till it sticks.
I did not reuse a home directory, nor did I do anything other than Install and try to enable Akonadi.
The issue does get much worse after updating the system, especially after the dbus and systemd update.
I finally got it to enable but only after messing around with other settings like Kwallet, Online services, search, etc., and repeated attempts aka hitting apply more than once. Even now, if I disbale Akonadi again it can not be just re-enabled and often have to go inand out of Plasma settings re-applying till it sticks.
I did not reuse a home directory, nor did I do anything other than Install and try to enable Akonadi.
The issue does get much worse after updating the system, especially after the dbus and systemd update.