Please verify the integrity of the game files in Steam
From the Steam Library, right click iRacing and choose Properties.
Then click Installed Files
Can you please confirm that this only happens on the Spa track?
Can you also let us know if you are updating from the Steam application, or the iRacing UI?
Please open Windows File Explorer and navigate to where you have iRacing installed (by default this is C:/Program Files (x86)/Steam/steamapps/common/iRacing), open the Tracks folder, delete the file named "tracks" or "tracks.dat".
Then log back into iRacing and try and install any updates and see if this resolves the issue.