Hi,
the supply.txt (event script, 1939 World at War) contains a few errors, so the reduction (i.e. malta effect, raiding near brisbane etc.) is not working as intended.
Though, quite easy to fix it manually; just open the supply.txt and search for [20] and replace it with [22] AND AFTERWARDS search for [18] and replace it with [20]. Now just update the script in the editor and integrate it.