Yay, there have been made various changes to the aligners. I’ve tested them as good as possible with many tools but obviously missed something.
In your case the top level vertical aligner is in the way. It’s not really doing anything because all the content is stacked by the main column already.
Using this as your main layout should do the trick:
local dialog_content = vb:column {
margin = 4,
spacing = 4,
vb:column {
style = "group",
margin = 4,
vb:row {
vb:text {
text = "Key "
},
-- and so on