fixed elements filtering

Former-commit-id: 77787407e2387a2e995f9792570052d0673368cc

lib/hooks/content/content-hooks-frames-web.js

@@ -318,7 +318,9 @@
 					let targetElements = observedElements.get(intersectionObserver);
 					if (targetElements) {
 						targetElements = targetElements.filter(element => element != targetElement);
-						if (!targetElements.length) {
+						if (targetElements.length) {
+							observedElements.set(intersectionObserver, targetElements);
+						} else {
 							observedElements.delete(intersectionObserver);
 							observers.delete(intersectionObserver);
 						}