You are today not the first one with this issue.
Seems like some UPDATES were done related to the functionality of dropdowns.
@yisrael-wix Perhaps you should take a look on this issue (it is not the first today related to dropdowns).
What you can try to do is —> delete the dropdown completely and add it again. Check if it got back it’s functionality.
https://www.wix.com/velo/forum/community-discussion/editor-bug-selectors-no-longer-valid
https://www.wix.com/velo/forum/community-discussion/unable-to-select-one-specific-element-code