Comment # 8 on bug 979775 from Fabian Vogt

(In reply to Stakanov Schufter from comment #7)
> Now updating this to Leap 15 were I was able to reproduce the same bug. 
> Thus valid for Leap 15

Does it work with

[Users]
ReuseSession=true

in /etc/sddm.conf?

I'm not sure why it's not the default. If not, this might be a side effect of
bug 1089287.