Yokai Event Bug

[Kirika-]

You are not experiencing a bug.
As you have already done the previous year(s) Yo-Kai Watch event, you can't "start" the quest over again.
However, you will already have access to the Watch, The Medallion, and the merchant NPC.

The Watch = Visit the Recompense Officer, of which you have already done, and just equip it for FATEs to earn the event currency used to purchase the minions. Have the minion out in the matching zone for FATEs to earn weapon currency (you do not need the Watch equipped to earn weapon currency)
Wandering Executive = Nohi = The event merchant. Once you do the event unlock quest, the Wandering Executive's NPC name becomes Nohi. As you already did the previous year(s) event, it is already unlocked and the NPC's name is Nohi.
Medallion = Look for the new Icon called "Open the Yo-Kai Medallion" in your Minions Guide, next to the "Edit minion hotbar" icon, or access it directly via Collection in the Duty menu.

To add:
If you already have a "name" minion, that minion no longer shows as one purchasable from Nohi. As in, if you already have purchased all the minions, he will no longer have any to offer you.
The currency required for each Yo-Kai weapon is unique to that weapon, obtained from doing FATEs in certain zones with a certain minion active, the name of the currency needed to a specified weapon is the minion required to be active to get. You can't purchase the weapon again, as it is Unique flagged. So, if you get carried away farming currency in one zone with one minion, once you get more than enough to buy the weapon, extra is worthless. For example, a "Legendary Robonyan F-type Medal" can only be obtained when you do a FATE in certain zones (Upper La Nos., N. Shroud, or S.Than) with "Robonyan F-type" minion active and can only be used to buy the MCH weapon only. The Yo-kai Medallion will show which minion covers which zone when you have minions populated in it.
Currency:
Yo-Kai Medal = Currency for minion purchase (1 needed for first minion, 3 needed for each additional minion).
Legendary "Minion Name" Medal = Currency for weapon purchase, 5 needed for first weapon, 10 for each additional, restricted to Minion Name Medal for Specific weapon only, see Nohi's weapon list to determine which minion is required to be active to get which weapon currency.