Thrall missing in production line

Game mode: [Singleplayer]
Problem: [Bug]
Region: [Germany]

Thralls are missing in the production line of the Wheel of Pain after loading the game and the progress of a previous session seems lost.

Steps on how to reproduce issue:

  1. Load the game
  2. Look at the Wheel of pain, thralls are in the inventory and the food is getting less but in the production line is nothing to see
  3. stop the process at the Wheel
  4. restart the breaking of the thralls, the thralls appear in the production line but the progress is set to the start