This reminds me of the strange way that memories of dreams behave:
Sometimes you still remember bits from a dream right after you've woken up - but this memory somehow vanishes rapidly and is gone a few minutes later. This despite you already being awake at that time and consciously having a memory of having had that memory. Only the memory itself is gone.
(Unless one had training and could capture the memory, e.g. in a dream journal)
Makes me wonder if this hints at some interesting neurological processes: It seems there is either some process in the brain that actively erases dream memories, or that dream memories are somehow stored differently in the brain than regular memories and only appear as the same thing to the consciousness. (Sort of like some part of the directory tree being mounted on a different file system)