Cleric - "This homebrew Subclass does not have the necessary class features with the correct required levels."

With the transition to 5.5, I’m unclear on the specific requirements for publishing a homebrew subclass for this class. I attempted to use the Light Cleric as a base, assuming it had the correct feature progression, but even the default subclass displays the error:

"This homebrew subclass does not have the necessary class features with the correct required levels."

From my understanding, a subclass should have features at levels 3, 6, and 17, along with a domain spell list at level 3. The newer Cleric subclasses also seem to have an additional feature at level 3. However, despite mirroring an officially published subclass, I continue to encounter this error and can't determine what I’m missing.

Could someone clarify the exact requirements for cleric subclass publication in 5.5? The homebrews how to faq just says "Refer to the class entries for the 2024 classes for information as to what levels are required and/or prohibited. Once all features are at the correct levels, re-save the whole subclass." and i don't feel that is helping me.