Jim, we are not in your head, we can’t see through your eyes, you have to provide some context.
What were you doing ? What did you expect ?
Which bug are you talking about ?
So you are talking about Ubiquity, the installer.
Depending of your choice of Installation ( beside existing OS, replacing everything or else ) it expects different things.
If « beside » it expects one empty, non-allocated, large enough space, to make use of it for creating and formatting necessary partition⋅s to finally install Ubuntu.
If « replacing » it will swipe everything and use the whole disk to install.
If « else » there you can do everything manually, formatting or re-use and point-mounting partitions as you wish.