In addition to what was already stated by Moralecheck -
While the game engine may sometimes allow it, you are not technically allowed per the game rules to load during the combat phase if those units cannot or will not be used for an amphibious assault during that combat phase.
Yes, I understand. I was assuming that they could be offloaded at some point that turn, but either way it would have ended up being the same if I loaded them in combat move or non-combat, since they could do nothing either way.
Pretty sure the Calc on this site and the TripleA Calc let you tweak the OOL. I forget how the TripleA one works but the Calc on this site has two text bars below the fields where you input unit quantities. One is for attacker OOL, the other is for defender OOL.