This is status-bydesign, not a bug. Only posts with negative score can be deleted outright by trusted users; see the trusted user privilege:
Trusted users are allowed to perform trusted actions, including:
- Voting to delete answers with score of -1 or lower
Emphasis mine; if the score of the post is 0 or higher, even trusted users only get to recommend deletion.
For example, I have 20k+ here on Meta, but for this review (post visible to 10k+ only) the post in question had a positive score when I voted to delete, so my vote was recorded as a recommendation rather than an outright deletion vote.