Comment 2 for bug 2045480

I've just ran into the same issue.

It's clearly a bug since this [1] blog post even brags about how it's now possible to wipe bitlocker'd drives.

There's a workaround: Open a terminal (by clicking on the dash-dot thing icon in the top left and searching for Terminal) and then running:

    sudo wipefs -a <device>

You can find the correct device with `lsblk`

[1] https://ubuntu.com/blog/how-we-designed-the-new-ubuntu-desktop-installer