Innocuous Researcher

• WOTC Official Reminder Textofficial rules
  Investigate — Create a Clue token. It's an artifact with ", Sacrifice this artifact: Draw a card."

• WWizards of the Coast2024-02-02
  Official Ruling
  Some spells and abilities that investigate may require targets. If each target chosen is an illegal target as that spell or ability tries to resolve, it won’t resolve. You won’t create any Clue tokens.
• WWizards of the Coast2024-02-02
  Official Ruling
  Clue is an artifact type. Even though it appears on some cards with other permanent types, it’s never a creature type, a land type, or anything but an artifact type.
• WWizards of the Coast2024-02-02
  Official Ruling
  If an effect refers to a Clue, it means any Clue artifact, not just a Clue artifact token. For example, you can sacrifice Wrench to pay for Alquist Proft, Master Sleuth’s activated ability.
• WWizards of the Coast2024-02-02
  Official Ruling
  You can’t sacrifice a Clue to pay multiple costs. For example, you can’t sacrifice a Clue token to activate its own ability and also to activate Alquist Proft, Master Sleuth’s ability.
• WWizards of the Coast2024-02-02
  Official Ruling
  Except in some very unusual cases, the card each player reveals is the one they’ll draw.
• WWizards of the Coast2024-02-02
  Official Ruling
  There’s no window for you to cast spells after untapping all lands you control but before the “you can’t cast spells” portion of Innocuous Researcher’s last ability takes effect. Once that ability resolves, it doesn’t matter whether Innocuous Researcher stays on the battlefield; you’ll still be unable to cast spells until your next turn begins.
• WWizards of the Coast2024-02-02
  Official Ruling
  Some abilities trigger “whenever you sacrifice a Clue”. Those abilities trigger whenever you sacrifice a Clue for any reason, not just to activate a Clue’s activated ability.

Rulings via Scryfall