unbuildable wonders in the build list.

[Toasterovnn]

I might be wrong but the game seems to let you progress wonders you can't actually complete. I went to build Weiyang Palace for the +6 influence but it sat on 1 turn remaining for 5+ turns. I assumed I was reading it wrong but when I went to check the wonder in the civopedia it turns out it requires the Jangzi civic, which I can't research. Am I just not civics tree correctly? is the civic in another era and I just wasn't able to read that part of the tree?
I was playing Isabela 1 as Egypt.

tl;dr
was able to start but not complete a wonder in my capitol because of a civic that didn't exist in my tech tree.

[back_buffer]

None of the wonders are locked behind a nation's unique civics. Weiyang Palace is also unlocked with Citizenship.

You probably just encountered a bug. If you didn't have the appropriate requirements, you shouldn't have been able to see it in your build list.

[{SLURP}Legion]

some nations unique civics unlock wonders so that they are easier for that civ to get since its their wonder. if you have a nation with a wonder in the unique civic, you can still unlock it the normal way but its usually easier to research the 2-3 unique civics to rush it than main path to it.

[Jiminy]

The same is happening with me. I have waited a few turns and it is stuck on 1. I moved it out and back in again and it didn't make a difference.
I'm playing as greece and Egypt is going to build it before me. very annoying.