Yes, they where able to provide proof no tracking had ever been made.
Look on reviews for the site, it seems to be a popular scam from them.
And look at reviews for Royal Mail?
Royal Mail is rated "Poor" with 1.9 / 5 on Trustpilot
Do you agree with Royal Mail's TrustScore? Voice your opinion today and hear what 120,238 customers have already said.

1.9 average across 120k reviews.
I'm by no means saying AliExpress are perfect, but I'm trying to point out to you that just because the courier in your instance claimed they never had an item doesn't guarantee it was the retailers fault. RM do not exactly have a good track record to suggest they can be implicitly trusted.