A recent update to Excel could be blocking all Excel add-ins downloaded from the Internet by default: more information at the official documentation.

To unblock Seccomp’s add-in, follow these instructions:

  1. Open Windows File Explorer and go to the folder where the add-in was installed (e.g., C:\SECCOMP).
  2. Right-click the file and choose Properties from the context menu.
  3. At the bottom of the General tab, select the Unblock checkbox and select OK.