Hello Tony,
thank you for your kind reply. I tried to reset the website and redo the theme installation and the demo import, but I have the same results. No demo images are shown and same slider issue.
I reset WordPress again so now it should be all empty. Please find in the Private content area my access credentials. The website is hosted locally, but I will leave xampp control panel open with MySQL and Apache running so you can do the importing.
Thank you again.