Spoiler below (I've been taking screenshots of the ones that I found really difficult A5 was one of them).
I must still be missing something, I can't walk through those ice blocks.
Oh. You need the thermal power up so you can walk on ice.
Dang I don't even know where that is yet.
All puzzles are completely solvable just some are really tricky. When you start getting into the ice flowers it gets quite challenging.