Are you ineligible for achievements your first run through story missions?

Completing Hot on my first character, I just kind of ran thought it paying no attention to achievements. Going through with my next character, I'm trying to complete them all as I go along, but looking at which ones I accidentally got my first time, it doesn't make sense how I managed to get almost none of them besides the "complete this mission" achievements. For example, I'm on "roots of terror" and there's an achievement for taking each of the 3 paths. I don't remember which I chose, but I had to have chosen one of them, since I completed the whole story before, and yet I have none of the 3 achievements. Are you only eligible after an initial play through? So basically I have to play roots of terror 4 times total at minimum to get all the achievements for it?

In LS2 story instances, you are ineligible on the first play through on each character. From HoT onwards, most achievements are available on a first play through, but there are a small number of exceptions that for some reason only work from the second play through onwards - taking the three paths in Roots of Terror happens to be one of those exceptions.

It's inconsistent prior to PoF. Some chieves in LS2 & HoT can't be done first time through. Some chieves in those stories & LS3 are either|or, e.g. kill all the things or kill none of the things. It's been a frequent source of complaints. The good news is that ANet seems to be moving away from that. The bad news is that they are unlikely to retrofit old stories to match; it's a lot of effort for a one-time benefit, unless they happen to be looking at the same code for other reasons.

I see. Well if nothing else anet is consistently inconsistent.