I know maintaining priority while in full control has worked in the past with no issues previously and still does but this following issue was a bit odd.

Attacking with an unblocked Leonardo, Sewer Samurai with a Leonardo, Cutting Edge in hand; able to be Snucked, and a Tayo, Lightshield Expert in graveyard.

Full control was active as well as manually tapping for mana because Tayo was the only Legendary creature in my graveyard while I had The Grey Havens on the battlefield, so I had to undo my tapped mana before putting Tayo on the stack.

Opponent has nothing on the battlefield or casts anything that would impact my play.

After placing Tayo onto the stack off of the unblocked Leo, Sewer Samurai's ability I was unable to sneak in my Leo, Cutting Edge before the Tayo resolved while in full control but after it resolved I was able to sneak as normal if I wanted to.

Also of note; in an earlier game, when I cast a Zack Fair from the graveyard off of Leonardo, Sewer Samurai's ability before it entered it trigger two on screen options to select from like it was a replacement effect: 1st Option: "Zack Fair enters with a +1/+1 counter on it" and 2nd Option: "During your turn, you may cast creature spells with power or toughness 1 or less from your graveyard. If you cast a spell this way, that creature enters with a finality counter on it." The selection may not matter but I selected the 1st option.