First of all, crypto needs to be done using newt ("install", not installgui). This is a known limitation of debian-installer and documented somewhere on the d-i website. Secondly, when installing from something involving an iso image, d-i will load the...

When installing from something involving an ISO image, d-i will load the wrong loop module and later on setting up loop-aes will fail. After generating enough randomness, you will receive the message "An error has occured while configuring encrypted volumes",...