The content watch keeps fetching nothing

#Four causes

Selector rot: after a redesign the old CSS/XPath no longer matches. Run Test rule once and look at what comes back.
Target refuses fetches: the site blocks crawlers and returns a verification page or empty response. Change the UA, route via your own node/proxy — see Advanced: fetch channels.
JS-rendered: the content is loaded by JS and absent from the initial HTML. Use the API JSON method to read the data API directly.
Fetched but wrong: the selector matched a different element. The test shows the extracted text — fix the rule against that.

Look for JSON-LD in the page first (offers.price-style fields) — most stable;
Let AI help you locate, then confirm with Test rule;
If it breaks often, try XPath or go straight to the API.