Describe the bug
On screens below 600px, the toolbar for blocks added in column blocks disappears when clicked. Also the toolbar appears to the bottom of the block, not the top. Not sure if that was intended.

To Reproduce
I added a columns block. In one of the columns I added the cover image block. In the cover image block, when I click a button in the toolbar (e.g. align text button) the entire toolbar disappears.

Screenshots

Desktop (please complete the following information):

• Chrome 70.0.3538.77

Additional context

• Gutenberg 4.1.1.

.