I experience this a lot, but on mobile, the active cast card takes up a big portion of the screen, frequently blocking the target of spells being cast. In the case of duplicated effects (eg, virtue of knowledge) where multi-targets take place, the card obstructs the view of what you're casting on. After one effect, the screen gets covered, and since sometimes a stacked target splits and moves the target, but on others when there's a slight difference a counter, the targets stay in place.

With other multi-target effects, it shows which spells are targeting which target, which makes it easy to target the correct targets. In scenarios like virtue of knowledge, the screen view is obstructed, it doesn't show which targets and targeted, nor does it show which spell in the stack targets which target, and sometimes moves the target on screen and sometimes doesn't, which makes it confusing when there are some stacked targets, some not stacked targets, and no history or indication which of the targets are targeted.

Adding a "tracer" or other kind of visual indicator linking the spell in the stack to its respective target would be helpful.