[Trados Studio 2015] Stuck at "Convert to Translatable Format"

Hello everyone,

I am trying to create a project from the default template. A customer has sent me a folder structure containing 450 .ttx-files. When trying to create the project without any TM or TB, the New Project Wizard gets stuck at the first step (Convert to Translatable Format), the progress bar for this step doesn't even appear. I left it running for 45 minutes already, and Trados is constantly using 25% of my CPU (probably 1 of the cores), and nothing else is happening. I am using a gaming rig with reasonable performance and 16 GB RAM, so that shouldn't be the issue.

Is there anything I can do to make this work?

Thank you!