Cannot activate The Dark/The Light - Hex-Sealed Fusion Effect Effect

  1. Bug description
    [Describe what the bug is in your own words.]
    The Dark/The Light - Hex-Sealed Fusion lets you substitute this card for any 1 Fusion Material Monster, by Tributing the Fusion Material Monsters on the field, including it to Special Summon 1 corresponding DARK/LIGHT Fusion Monster from your Extra Deck. I have all the requirements but the game does not allow me to activate The Dark/The Light - Hex-Sealed Fusion effect.

  2. Bug reproduction steps

    [Write the exact steps to reproduce the bug. Provide a replay code if you can. You can attach replay codes, or use a pastebin link or you can even use a spoiler tag using]

    Spoiler

    your replay code

  3. Screenshot OR error code

  4. Expected behavior
    [Tell us what should have happened when the bug occurred.]
    It was working before!

  5. What OS are you using
    [Windows-10 / Linux / Android]

Online or Offline?

Additionally, please specify which monsters you are trying to use as materials and which monster you are trying to make.