Code inserted but ads not showing

Looks like the code is properly inserted.

Blank AdSense blocks are quite common:
https://adinserter.pro/adsense-ads#ads-not-displayed

thanks. the ads sometimes appear later, and there’s nothing wrong with my adsense account (not suspended or anything). any ideas?

Hard to say.
Google decides when and what ads will be displayed.

Usually after the code is inserted google needs some time (hours) to check the pages.

Now I see ads normally.

@spacetime Does the new insert feature works with WP-Rocket? Client side detection?

Yes, client-side insertion is done by Javascript code when the page is loaded in the browser so it works also with caching.

The latest version supports also server-side insertion before/after any HTML element so you can generate and cache pages with such insertion.
To enable it you need to first enable Output buffering (tab * / tab general).