Dhampirs, Negative Healing, and Heal

So this has come up in a discussion, but what should happen by RAW if you use 3-action Heal on a dhampir?

A dhampir is not undead, but has negative healing, which states: "It is damaged by positive damage and is not healed by positive healing effects. It does not take negative damage, and it is healed by negative effects that heal undead."

Heal states: "If the target is a willing living creature, you restore 1d8 Hit Points. If the target is undead, you deal that amount of positive damage to it, and it gets a basic Fortitude save."

So a dhampir, as written, isn't undead, and thus doesn't take damage, but also can't be healed from positive healing, and thus gains no health. Is this intended, or an oversight?
If it's an oversight, should things like Holy Cascade or Searing Light also treat the dhampir as undead?

(I am aware that by RAI it should likely be taking damage.)

I think Paizo/RAI wants the ability asymmetrical so that Dhampir can travel with normal PCs without affecting AoE Heals. The lack of "that damage undead" for positive energy seems intentional and means Dhampir are still counted as living for positive energy damage. This seems to nullify every instance I can see of positive energy damage except the Jyoti's whose breath affects regular living creatures anyway.
So yeah, for positive energy, Dhampir are in the living category and simply cannot benefit from healing (though other effects apply). And for negative energy, they are in the living category except for effects that heal undead, and they're otherwise immune to negative damage (but again, other effects may apply for which they'd count as living).

Oddly this could lead to situations where a Dhampir gets hit by a negative attack that damages (but they're immune) and imposes a condition (which they'd suffer), though in some cases it may be assumed that if undamaged the condition doesn't get through.

A few effects would damage a Damphir, for example:
Ghost Charges
Spirit Barbarian bonus damage
Life-Giving Form
Pharasma's Avatar Form
Ki Form
Ki Strike
All these deal positive damage without the target needing to be undead.

Essentially, it just nerfs you by not being able to heal with Positive healing effects. You aren't undead, but are treated as undead when it comes to negative energy.

Dhampir are treated as Undead for "Positive Damage" (Positive) per RAW. However, they do not take damage from Positive effects that don't deal damage.
Many vitality effects don't deal damage though, so they're usually fine. Dhampir's will take damage from Heal, but not from the healing ability of a bard. If a healing spell doesn't have vitality or void it will also heal them. This used to be true with Life Boost, until after the recent remaster.

I haven't found Negative Healing in both the Player Core 1 and GM Core, so I assume it'll be handled in the Monster Core. I hope we will have more directions at that time as RAW doesn't sound intended.

Negative Healing = Void Healing

Void Healing is present in GM Core.

GM Core also defines Vitality (Trait) and Vitality (Damage Type) as 2 separate things.

Vitality (Damage Type) states: "... damages only creatures with Void Helaing (such as undead)."

Heal states: "If the target is undead, you deal that amount of vitality damage to it ..."

That means to me that Heal would only damage Undead and not "creatures with Void Healing"

Just my 2 cents