Sounds like you have partitions causing confusion.
When you clone a drive with something like Acronis which is what I use, the cloned drive does not have a drive letter so it's invisible when you open file explorer.
As you probably know it's easy to assign a drive letter via disk management.
When you install windows there are also partitions that are not visible, MS does that I'm sure so people don't get confused with all those little drives and they are for backup after all.
I've never dealt with cloud storage, just a soon have my own cloned drives for back up, been doing that for years. Can't help you with that.