After selecting the 'Combat supply' button in the unit 'Withdrawals' list, the combat supply triangle on the 2nd FsJ unit counter goes blank.
In the 2nd FsJ unit info panel (on the right of the image) the 'Combat supply' has gone to level 4, when the highest game level is 3 (green triangle). [&:]
The overall supply level in the lower main screen info bar shows (7), it was (17) and a loss of (10) supply points, so now confused as to what this button in the Withdrawal list does, as it doesn't seem to give supply back. [&:]
The 'Supply and Fuel Status' panel shows supply consumed this turn as (10), so that equates to 3 levels of combat supply being lost, not regained.
When I cancelled this action, the unit went back to combat supply level 3, but the overall supply status only restored to (12), instead of (17), so (5) supply points gone for good. [&:]
Am I misunderstanding what this button does, or have I found a bug. A control to recover supply from units leaving the theatre is a very good idea, but it does not seem to be working.
The fix is, don't use the 'Combat supply' button in the unit 'Withdrawals' list, it is also good practice not to load combat supply into units which are about to leave the theatre.