1. Capture (by force) an enemy city that was previously an Independent Peoples'
2. Try to develop new districts there

Reproducibility

5/5 for this specific city post-capture

Once overall as I haven't been able to replicate the bug with another city yet and no longer have the save prior to this city capture (it was low stability at time of capture - so the restriction seemed fair to begin with), another enemy city I captured earlier was previously an Independent but did not experience this bug.

Expected Behavior

I should be able to build any potential district once a city is above the required stability level.