Assistance with Warlock sourcebooks with pact innocations

Sorry if this is not the right space for this but I was running through character creation for a warlock pact of the chain on the website, and when it came to picking innocations I found one I was unfamiliar with and wondered if someone could help me identify where it's from. I tried toggling on and off different sourcebooks and it never disappeared but every sourcebook I've checked it doesn't come up and tried googling but to no avail. I can attach a screen shot if necessary but it's called:

"Primal Summoner" - 

You can summon even more monstrous familiars to your side. When you cast the find familiar spell, you may choose one of the normal forms for your familiar or one of the following special forms: blink dog, death dog, panther, or worg.

Additionally, you can spend a bonus action on your turn to command your familiar to take the Attack action against an opponent of your choice.

Any help would be great just curious which source book it comes from or if some how Its homebrew. Thanks!

Primal Summoner is from the third-party adventure anthology Humblewood Tales. See here.

Thank you! That is really interesting, especially since I don't own that book it's weird that I'm able to access that content when building a character maybe a bug of some sort. Thanks again!

No problem!

You are likely in a campaign with someone who owns it and has content sharing turned on.

I think it is a bug and lets you use it without the content

For anybody else stumbling upon this, I find that the invocation only shows up when taking the Eldritch adept feat, and only for it. It also only shows up for the 2014 version of warlock. Hopefully it isn't the same for everybody else.

Quote from Cappuccino_***** >>

For anybody else stumbling upon this, I find that the invocation only shows up when taking the Eldritch adept feat, and only for it. It also only shows up for the 2014 version of warlock. Hopefully it isn't the same for everybody else.

The invocations added by 5e sources only show up for the 5e version of the Warlock, which appears to be by design.