Thank you for making a bug report!
Master Duel, just like Legacy of the Duelist (Link Evolution included) also uses the OCG rulings for Seal of Orichalcos. Its an OCG centered game. As such it uses OCG rulings and OCG card text, even if it shows the TCG card text (its a translation thing).
Regardless, in the TCG, you must be able to perform a mandatory action in order to activate a spell card. You can refer to Yu-Gi-Oh! TCG Product Errors to see what the text would need to say in order for the card to function similar to how it does in the OCG. The card needs to state “if any” in order for it to be able to be activated without applying its effect to the field. As such, as it is written, you must destroy at least 1 card on the field that was special summoned in order to successfully activate The Seal of Orichalcos.
As described, this is functioning as intended.
Once again, thank you for making a bug report. If you have any other questions please feel free to reach out on the Duelist Unite Discord Server in the #rulings channel.