Dear @SebastianS
did you try this?
No images are shown when you click "+Image"? Disable "Jetpack" plugin.
Projects do not show up?
http://laytheme.com/troubleshooting.html#nothing-shows-up
http://laytheme.com/troubleshooting.html#projects-dont-show-up
Is Wordpress and Laytheme up to date?
Did you install Laytheme on an fresh & empty Wordpress installation?
Maybe it is your webhost.
Did you try to run the website locally on your computer with MAMP?
Many questions…
:-)
Best!
Marius