Understanding how students engage with feedback is often reduced to a study of feedback messages that sheds little light on effects. Using the emerging notion of feedback encounters as an analytical lens, this study examines what characterizes productive feedback encounters when learning online. Drawing from a cross-national digital ethnographic dataset, a qualitative analysis categorized feedback encounters within this dataset: While most encounters led to "instrumental" impacts without any significant reflections, students also engaged in encounters with more "substantive" impact on learning. The latter took place under two conditions. First, the encounter must "challenge" the student's assumptions about their work, and they must be able and willing to accept this challenge. Second, the encounter must take place at a "time" which is appropriate in relation to whichever task the student is currently working on. This highlights design considerations, such as importance of social interactions, and the instrumental enactments of self-generated feedback.