In the current webUI design, we show you information on what mount points are "required" only on the "Mount point assignment" screen (and, sometimes, on completion of that screen), but the "Modify storage" link (to launch blivet-gui) is shown on the "Installation method" page, before you reach "Mount point assignment".

So at the time you get to create partitions, you've received no information about what partitions you're actually required to create.

I can't see an obvious fix for this, but it's not a great experience.

Reproducible: Always