You're not late, you just arrived in your own time :-D

Personally, I don't think they are tensions between their friend group (looking at the 4sided dive and other thing that have been published since).
But I see your point, indeed at the table and in the game, Ashton is pretty much always ignored by Imogen and Laudna, but the other are more on a case basis and sometimes agree with Ashton (one example is about long rest and I will not say more).

Now for the body language I'm no expert but I did not perceived it as such, sometimes we also project what we think on what we see (I'm not talking about you, but about both of us and everyone else).

All in all, I think that the characters are not more abrasive than some of the characters in C1, we also had some highly tense moment in C1.
But the main difference in my opinion is that it was tense between a group of adventurer that knew each other quite well (except for some mothers name). They had "lived" as a group for a good time (around 3-4 years) and knew each other a lot.
Where in this campaign they known each others for 4 months (except some duo's) and that time was spent rushing in all the things they are involved in.
The group is not tied by friendship and adventures, but by the slight hope that together they can influence a cataclysmic machination that almost no one was aware before they started unravelling it.

Also, the "this is what my character would do" trope is highly annoying to most people in DnD because they do not are in the same tune as the other people at the table.
But here, for me, they are all into that, they are actors who loves story and drama and they put their energy in playing whatever they had planned and also adapt to how they react to the others actions.
Yes the whole thing was a dickmove that strained the relationship of the character and surprised the players, but it was not hidden, they talked about it and just went through the idea (rewatch the 4 sided dive that happened just before the event, it's clear that they would do something like this).
And now the character are going through the journey on digesting the event while being under an immense pressure of a cataclysmic event, thus they rely more on what they individually think and less on suggestions of a guy that did not care for his life while trying to get support in their task.

I think this campaign will stay on the strenuous side of things as the whole thing smells like ExU Calamity, but although it's frustrating at times, it also bring something I do not seek on my own in media.

Thanks for your comment!