Achievements not unlocking?

I’ve seen this pop up a few times already but they all seem to be because people are playing both on windows and xbox. For some reason some of my achievements aren’t unlocking. For instance, the achievement for all perks unlocked. I’m lead to believe it may be down to the fact i unlocked some perks offline? If anyone has any answers that would be great thanks.

Yes I play on both and I think I did my final festival upgrade while offline and my Like A Boss has not unlocked.

Earning achievements while offline is, well, strange. Sometimes it registers when you come back online, but in a lot of cases it won’t at all. That happened to me with Dirt Rally.

I have a heap of FH1 achievements that never unlocked, but I think I did receive the points anyway.

I’ve a load for both Horizon 1 and Motorsport 4 that did unlock, but aren’t registered in the Forza Rewards. Those ones were earned when I didn’t have any Internet after moving house. Mostly the early achievements there, which I would have to have in order to have the achievements that are registered there. Like I said, offline achievements are strange, especially for Forza Rewards.