Nothing is being produced - Anybody else with this problem?

[Adagio]

I'm playing Civ 6 for the first time since the release of Gathering Storm, which I haven't bought yet. Continuing my save from before release and I can no longer build any wonders in any of my cities for all my wonders.
No big deal if this is just because I'm continuing an "old" save as I wasn't planning on building any more wonders as I'm close to to the end of the game