Not sure whether this qualifies as a “bug” but there are several combinations of objectives and maps where the echo starts before you get inside or (separately?) will begin before you start moving. One such example is “Slay the Spine Hunter Alpha” on the map “Alpine Halls”. There are many examples of this – it happens on some of the echos that are surviving arena-like waves, or ones where you have spires launching things at you from across the map. It’s definitely not the majority of times, when loading into an echo, but it is happening where you load in and you’re already in combat with mobs on top of you (online, single player, with minions).
Thanks for reading!