Moving Players Pre-Snap
I notice when playing, if I want to move a safety or linebacker closer to the line of scrimmage they seem to move their feet but be stuck in the same place. It’s like a magnetic force field stopping them from moving even though you are manually trying to place them in a different spot on the field. In addition to this, in the case you do get to move the player manually sometimes when you move them and click off to a different player they go right back to where they were before you moved them.
What you are describing actually sounds intended to help prevent them from going off-sides and shift them into a position so they properly perform their coverage. This helps prevent exploits too where players used to position certain defensive players on the field to confuse the AI, leading to instant sacks.