Has anyone tried if it works to navigate through poles in 744X or if theres any major issue to prevent this? Im planning to maybe try this tomorrow, hoping it will work :)

Tried it and didnt work perfectly yet. The LNAV and the magenta route line seems to go perfectly fine up to the pole, but after crossing the pole things get crazy. Hopefully in the future it will be possible to cross the poles with LNAV. This time my solution was to use HDG SEL mode to navigate to lower latitudes and then engage LNAV again.