Chains of Light against a Dragon?

"The creature is paralyzed and held in place"

I was reading the description and it seems those two are independent effects... While the dragon wouldn't be paralyzed because it's immune to it, they would still be held in place.

Hard to know for sure if it was just loose wording or an intent for it be a separate effect.

It would lock them to specific squares/cubes, would be one valid interpretation.

Ultimately you'd have to ask your GM.

If being held in place is a secondary effect of the paralysis then dragon immunity to paralysis covers it ('A creature does not suffer any secondary effects that would normally be triggered by an effect it is immune to.') I think this'd cover it but I'm not certain.

Yeah, we simply don't know if "held in place" is descriptive text, a secondary effect of paralysis, or intended to be a separate effect from paralysis.

I would probably rule it's a secondary effect of the paralysis, and thus the dragon would be immune.

Personally, as a GM, I'd say that the Dragon is immune to the paralysis and physical movement effects. If it fails its save, I'd just rule that the chains of 'light' manage to wrap around it but find little purchase to physically restrain it, just hanging off of it while still preventing the magical movement the rest of the spell describes.

Then again, I operate under the 'fail forward' school of thinking for this game. You still got to do something, even if it wasn't entirely what you expected.

I'd agree, I'd rule a dragon or any creature immune to paralysis also immune to the effects of this spell.

But hurray for vague wording! The main issue is "held in place" isn't a technical term and isn't sufficiently different than "paralyzed" to warrant treating it as a secondary effect.

CRB:
Paralyzed: “ A paralyzed character is frozen in place and unable to move or act.”
Hold Person: “ The subject becomes paralyzed and freezes in place.”
Chains of Light: “ The creature is paralyzed and held in place”

I would view it as fairly clear that the ‘held in place’ language is explaining what ‘paralyzed’ means. Hold Person’s “and freezes in place” is just repeating the definition given by the Paralyzed condition, and is clearly not a rider effect, and the same structure is used for Chains (albeit ‘held in place’ instead of ‘frozen in place’, because ‘chains’).