Just found this bug by accident:
Your own valour flag does not work correctly, untill you have recaptured it. At start, you own the flag, but it does not work untill you have lost it, and then captured it back.
At least that's what happened in last game, on Crucible map.
It was one of those looong games, with huge amounts of money around. Me and my ally pushed right at the enemy citadel, (and captured their valour flag while at it), but then my ally disconnected, and the AI started to lose badly. We were pushed back to the middle of the map. That's when I noticed it. Both sides had everything creep related maxed, max damage on creeps and max armor/HP. (At this point they had recaptured their valour flag.) Their giants had 2800 something HP, and our giants had 2310 (or something, could have been 2130, didn't write numbers down.) Nothing explained the difference. We got pushed even further as time went on, and soon enemy captured our valour flag. Their giants HP went above 3000, BUT OUR GIANTS HP WAS UNAFFECTED. I managed to recapture our valour flag, and only then did our giants HP go to 2800 something, same as the enemy giants.