KDE saves and restores all but Google Chrome in its Desktop saved session

For some reason when enabling Restore manually saved session in Desktop Session Login and Logout settings, and hitting Save Session from the applications menu - all opened application windows get saved and restored upon login into the KDE session, except google chrome.

I located the session file ~/.config/ksmserverrc and indeed firefox and many other applications are there:

$ grep firefox ~/.config/ksmserverrc
program11=firefox
restartCommand11=/usr/bin/firefox,--sm-client-id,10686f70[...]
$ grep gkrellm ~/.config/ksmserverrc
program12=/usr/bin/gkrellm
restartCommand12=/usr/bin/gkrellm,--sm-client-id,10686f70[...]
$ grep chrome ~/.config/ksmserverrc

as you can see chrome is not there.

And no application has been configured to be excluded:

$ grep excludeApps ~/.config/ksmserverrc
excludeApps=

The only unusual thing about chrome, as compared to other applications, perhaps, is that it appears as many threads in the output of ps(1).

I have it installed as:

$ sudo apt-get install google-chrome-stable
google-chrome-stable is already the newest version (69.0.3497.100-1)

My setup: Kubuntu 18.04, Plasma 5.12.6, KDE Frameworks 5.44