Tapped for mana events should still fire when no mana produced

[matoro]

605.2. A mana ability remains a mana ability even if the game state doesn’t allow it to produce mana.
Example: A permanent has an ability that reads “{T}: Add {G} for each creature you control.” The ability is still a mana ability even if you control no creatures or if the permanent is already tapped.

https://www.tumblr.com/magicjudge/71264631258/if-i-have-a-gaeas-cradle-enchanted-with-wild

If I have a Gaea's Cradle enchanted with Wild Growth, and no creatures in play, can I tap it for {G}?
Yes. Gaea's Cradle always has a mana ability, even if you have no creatures.

Fixes #15362

I believe that since ManaOptions uses different logic, this won't take the potential mana you could make into account when highlighting cards as playable/not playable, but you can at least manually activate it and pay from floating.

[matoro]

Btw, I think this directly conflicts with this ruling on [[City of Shadows]]

You can activate City of Shadows's second ability while it has no storage counters on it, though it won't add any mana in this case. You did not tap it for mana, though, in case any abilities (such as the ability of a Fertile Ground enchanting it) care about that.

[github-actions]

City of Shadows - (Gatherer) (Scryfall) (EDHREC)

Land
{T}, Exile a creature you control: Put a storage counter on this land.
{T}: Add {C} for each storage counter on this land.