So regrettably the Ironman Cloud Save functionality for new saves started in 1.21 has broken. We have a fix in work and hope to release a hotfix for it as soon as we can.
In the mean time, you can save Ironman games locally, or non-ironman games on the cloud. If, like me, Ironman Cloudsaves is a necessity in your life, then there is a workaround:
1) Start a new non-ironman game.
2) Save the game to cloud with the name you want for your ironman game.
3) Go back to menu.
4) Start a new Ironman game.
5) When prompted for a name, select the already created regular cloud game.
6) Start up game and save without problem.
We apologize for the inconvenience and are working to get it fixed as soon as we can.
In the mean time, you can save Ironman games locally, or non-ironman games on the cloud. If, like me, Ironman Cloudsaves is a necessity in your life, then there is a workaround:
1) Start a new non-ironman game.
2) Save the game to cloud with the name you want for your ironman game.
3) Go back to menu.
4) Start a new Ironman game.
5) When prompted for a name, select the already created regular cloud game.
6) Start up game and save without problem.
We apologize for the inconvenience and are working to get it fixed as soon as we can.