Black screen on cold boot with full disk encryption

Hello,

i recently installed Trisquel on my desktop with full disk encryption.
With this setup i experience a strange bug which causes the system to freeze while booting up.
The problem is fixed easily by pressing the reset button to repeat the POST.
Without disk encryption i did not experience the bug.

This error only appears when installing Trisquel with full disk encryption and LVM.
At first i thougth my partitioning had an error but it appears that the bug exists even with the auto partitioning of the installer.

Did anyone experience similar problems or can provide some advice where i could start my error hunt?

Thanks in advance