This is not specific to you, effectively there's a problem (regression?) in the test, since start of July many people got the same problem as seen on Stack Overflow or Reddit.
As the post on Stack Overflow got deleted, along with my answer, I'll reproduce it here:
Explanation
The challenge is bugged.
To display the hint, the page verifies that the reduced structure that will get displayed in the hint (color =, note it is trimmed down, starting with a c and ending with an matches regex isEqualsOrNotEqualsPattern = /\s*(.*)\s+(IS|=|<>)\s+(.*)\s*/i;.
If you look closely, you'll see that it is looking for a \s+ after the =, that is, at least one space. Which misses from the trimmed down structural keywords. So it will always fail, not even on your SQL, but on the expression they hardcode as the expected structure of your SQL.
What you can do
Just hack the page. This validation code is superficial, just for giving a hint, not what will validate that your solution is correct and allow your test to be marked "passed" and saved.
So when the grayed button Next appears, use your browser's inspector to find it in the DOM of the HTML page, and remove its disabled and aria-disabled HTML attributes.
Then you can click on Next: it will save your (correct) answer and get to the next problem.
But it will be tedious: at least the 3 next tests use this bugged validation. I didn't try to go further.
What Cisco can do
Fix the Javascript (or make clear this is an SQL and DOM hacking assessment).
