I have the same or I can for some reason further the plot and I just replay the same scene over and over. The only time I can really get deep into my world is when I'm laying down with some light music

P.S Or when I'm half asleep

Dealing with that right now, I feel like I'm grasping at smoke trying to get a daydream to stick but nothing is staying for long

I get this too, it's happening more and more with age, my imagination just isn't as strong anymore I guess. I get into daydreams hard when something really inspires me, like when I discover a new movie or crush or person that I feel intimated by lol...but thats harder and harder to come by these days. Im just not as obsessed with people or things as i used to be. My triggers are less effective, my sessions shorter. Its like a drug and our tolerance is growing lol