Describe the bug

When using Shift+ArrowDown to create a multi-selection, it is not possible to select more than two blocks of the same type†.

† "Of the same type" is important to note because the block transform toolbar option only appears when the multi-selection consists of blocks of the same type. I suppose it should also be noted that it might only be an issue for blocks of the same type which have transform options.

To Reproduce

Steps to reproduce the behavior:

1. Navigate to Posts > Add New
2. Add three paragraphs
3. Select the first paragraph block
4. Shift+ArrowDown to select all three blocks
5. Observe that after the second block becomes selected, the next Shift+ArrowDown causes focus to be moved into the transform modal, rather than continuing the multi-selection.

Expected behavior

I should be able to multi-select as many blocks as I continue to Shift+ArrowDown.