The most common cause is a missed interaction requirement. Keeper's Altar only works at night, the target rod must be equipped, and you must be holding an Enchant Relic when you interact with the altar. Check those conditions in order before assuming the game is broken.
Check the Time: Night Requirement
The Keeper's Altar is only active at night. If you're standing at the altar and nothing happens, verify that the in-game time is night. This is a reported limitation of the altar's functionality.
Equip Your Rod and Hold the Relic
The second requirement involves your inventory state. To enchant, you must have the rod you want to enchant equipped, not just in your inventory. You must also be holding an Enchant Relic when you interact with the altar. If your rod is unequipped, or if you're holding a different item, the altar won't respond. Confirm both conditions are met before proceeding.
Find the Correct Altar Location
The Keeper's Altar is located in the Sovereignty Mines. You reach this area via an elevator from the Statue of Sovereignty after speaking to Cole. Make sure you're at the actual Keeper's Altar used for enchantments.
If It Still Doesn't Work
If it is night, the correct rod is equipped, the relic is in your hand, and you are at Keeper's Altar, the interaction should work. If it still fails, the problem may be server-side or update-related; no reliable extra fix has been confirmed. Check current Fisch announcements or report the issue before trying unverified workarounds.