hm...
stupid question: WHAT exactly is the problem?
cant you ship into the area?
or
cant you disembark and invade?
*********
Startetd with 1.01 Quebec and ended / testing mods with 1.02 getting Hawaii was never an issue for me
if the game is just talking about you cannot enter the sea region, it could simply mean the maximum distance from a harbor is too long.
I remember it was impossible for me to get the US American Pacific Fleet from the western coast to the Phillipines, for the torpedo boats could not run that far. I had to exclude them from the stack.
but i dont remember if i got the identical message from the game...

...not paid by AGEOD.
however, prone to throw them into disarray.
PS:
‘Everything is very simple in War, but the simplest thing is difficult. These difficulties accumulate and produce a friction which no man can imagine exactly who has not seen War . . . in War, through the influence of an infinity of petty circumstances, which cannot properly be described on paper, things disappoint us, and we fall short of the mark.‘
Clausewitz