Thank you Roman
While I was trying to create a user for support, I solved the problem finally.
I reactivated Autoptimizer with basic js optimization (plugin was deactivated because it had broken my bootstrap slider),
And miracle: this time the Bootstrap slider played always correctly AND the Layer slider showed up suddenly!
Now all features in evolve are working fine
Thanks also to Frank 😉 Guess he made an update recently
Reply To: Image Slider: last thing that doesnt work since theme switch from free evolve