Steps to reproduce:

1. Control Satya, Aetherflux Genius.
2. Attack with Satya targeting Exalted Sunborn cast using warp, or otherwise create a tapped and attacking token copy of Exalted Sunborn with Satya.
3. Exalted Sunborn’s replacement effect creates an additional token copy, so two tapped and attacking Exalted Sunborn tokens are created.
4. Move to the beginning of the next end step.

Actual result:
Arena does not allow me to pay energy to keep the Exalted Sunborn token copies, even when I have enough energy available.

Expected result:
Satya’s delayed trigger should allow me to pay energy equal to the mana value required by the token copy/copies created by Satya. If the total payment is required for both copies, Arena should allow payment when I have enough energy. If payment should be handled separately, Arena should allow keeping the relevant token copy/copies by paying the appropriate amount.