As far as underwater gathering is concerned, I believe that the reason Miqo currently struggles with it has to do with how it treats dismounting when flying to a node. In a normal flying zone, Miqo seems to dismount slightly above a node if it flies directly to the node. Even if it initially stops in midair outside of gathering range, the act of dismounting puts it in gathering range. However, underwater, if Miqo approaches a node from above, then it will stop and dismount like normal. However, this dismounting action does not lower the character to a position within gathering range like it does above water. This is why I believe it gets stuck. A possible workaround until stage 2 is released is to make your navigation grids such that Miqo never approaches the node from above.