I had the same issue described in this post by @marktuff and found the same workaround myself. While I’ve just moved on with my app, isn’t this behavior actually a bug?
According to the reference, a dropdown with no content selected AND the “this input should not be empty” checkbox marked should be marked invalid by Bubble if the dropdown contains no content.
In my example below, Dropdown model “should not be empty” yet the inspector shows it to be valid when run:
The reference refers to being marked invalid for workflow purposes, but this should also hold true for conditions, right?