Hey guys,
With the new form, once you have selected a single select, if you click on the field again to make changes, it only shows the option you have chosen, making you have to “unclick” it and then choose again.
It confused me at first when I didn’t see the other options, so if it confuses a guy building product, it would probably confuse a not so tech-savvy user. Just a suggestion to go for the best practice and show all options again when the block is clicked 
(pic below)
Happy Wednesday!