L405 Anti roll bar knock

Currently working on a 2015 L405 with a knocking coming from what sounds like the front suspension, we've replaced almost every part of the front suspension, including both lower control arms, upper wishbones, anti roll bar drop links, both air struts. Although this has significantly improved the noise, there is still a knocking when going over bumps. The next part I'm looking at is the active anti roll bar, but unsure if there is a way to tell if it's bad?

Check there isn't any air in it - are the bushes OK? Generally they leak if there is internal wear causing a knock, does it knock if you go over a speed bump at a 20-30 degree angle?. If it only happens when going over a speed pump straight on, it won't be the ARB, but could be the bushes.

Replace the bushes and the drop links again, it appeared that one of the drop links that were installed had a bit of play in it so all sorted now, thanks