Can't install experimental modules A follow up to this thread: Can&#39;t install experimental modules

I've installed Drupal 8.2.5 two times on my server. First with the "minimal installation" option, and after that with the "normal installation" option. In both cases the installation worked without any errors. But in both cases I can't install experimental modules. I set the check mark next to an experimental module, then click install, the site refreshes and nothing changes. I can install other modules just fine. Since I must upgrade an existing Drupal 7 installation, I need the experimental Migrate modules. 

No error messages are given, neither in "reports" nor on server level. Does someone know why this pre-alpha-like error occurs and how to avoid it?
Use drush to install it.

In case that don't work, try installing only BigPipe module to see if it is really a Core(experimental) modules problem or it's just some modules that are problematic and still need more development for drupal8 application.
As it is written here the only stable experimental module is BigPipe.