Never trust the chat agents! They are almost always misinformed and cannot be considered a reliable source of information or trusted to make changes to itineraries. FT is full of horror stories of chat agents screwing up reservations.

If you just earned Platinum, and select your 2025 choice benefit of 4 RUCs today, they will be valid through 1/31/26. You won't get another set or have any ability to choose another choice benefit until you requalify for the 2026 medallion year throughout 2025.

Also, I highly recommend reading the thread on RUCs: Using Regional Upgrades on Delta (RUC) post 2/1/2022

Lots of good info here and what to expect with RUCs. Spoiler: They are not user friendly, and while they have some value, expect frustration in finding availability, having the upgrade survive schedule changes, and difficulties checking in. In other words, proceed with caution.