it's historicaly acuruct the battle of long island was the biggest battle of the war which saw the amricans outnumberd 10 to 1 leding to fall new york

Well, I put 6000 men in New York. The AI took Hempstead but did not attack New York. They just walked up close, till the point you can see in the foto right here, and then went back again. The next winter i starved them all out - quiet weird. Is it an AI issue?

Not a glitch. They had 16k when they dropped in on me, but if you abandoned Hempstead and New York you might be able to get them to split their forces. Then bait the NY garrison out so you can rout them and gain the numerical advantage. Use Ft. Clinton to stop them from moving out of NY

Not a glitch. That's a stack of over 10k, being held back for now due to your 4.4k. I was in the same situation and they ended up routing my force out of New York. Next time I just let them take it. That force is specifically to occupy New York so they shouldn't push out from there to my knowledge

Its not a glitch, you probably have close to the same amount of men combined in your army you just have to get them there.