Game is not saving itself on a specific save - No Mods/All DLC

For an Ironman campaign, you choose at the start whether it will be stored locally or in the cloud. That setting never changes.

For non-IM games you can choose each time you do a manual save whether it is cloud or local.

I'm not aware of any circumstance when a local save gets 'converted' (uploaded?) into a cloud save!  

Legion4 said: it'd at least be nice if the game could have a warning when this happens.

Probably worth lodging it in Bug Reports then. You mention the MS cloud so I assume this is the Gamepass edition of the game; be sure to mention that there too.