Board Thread:Manga/@comment-44086949-20191205133131/@comment-37493549-20191224171032

Oh and since I didn't clarify, you can of course make the case that Zeke might be able to feel Grisha within the memory world. Eren and Zeke don't fall through the ground in the memory, they're shown leaning on parts of the scenery, and opening 'doors' to move from one memory to another. (Which obviously weren't there in reality when the memories actually happened, much like Eren and Zeke aren't really there)

So while Zeke might be experiencing the sensation of Grisha touching him (just like he's presumably experiencing the sensation of solid ground beneath his feet etc), Grisha himself can't. He can only experience the things Eren is experiencing (the visual and audio); Eren isn't hugging Zeke.