Can't login to Hikashop site with their ReCaptcha enabled

We're using SCLogin and JFBConnect. I have a Hikashop site that has the Joomla and Hikahop Recaptcha plugins.
The ReCaptcha is only displayed on the registration form (a requirement for us) when the Hikashop plugin is enabled.
With Hika ReCaptcha enabled, I'm not able to use any social login. I've done lots of testing various scenarios in hopes the detail provides a clue.

It looks like it's trying - a Joomla account is created, but no Hikashop user is created. The account shows up in the User Map but the user is not logged in.
Initially the user gets a message that the account was linked, another message at the same time indicating "The CAPTCHA solution was incorrect".
Subsequent attempts still fail but with just the Captcha error message. If the Hika Captcha is disabled, I'm able to use social logins and the Hikashop user is created.

Once the Joomla and Hika users are created and there's a mapping in JFBConnect, login works reliably even with Captcha plugin enabled.
Is there something I may be missing that breaks authentication when Hika Captcha is enabled?

The problem is that with automatic registration and the Hikashop Recaptcha disabled, no captcha is presented on registration. I've confirmed configuration both for the site default and user options reference the standard Recaptcha, but none is displayed.

I prefer not to disable automatic registration - then social login provides very little benefit.
With the Hikashop recaptcha enabled, captcha is presented on registration for users that don't want to use social login, but automatic login via JFBConnect is creating the Joomla account, not creating the Hika account, and displaying an error.

Of the two options, Hikashop's Recaptcha makes more sense as it also presents on comments and contact forms being submitted.

With your assistance, I was able to resolve this.
I created another site for testing and noticed that the Joomla Captcha was being displayed on registration, social login worked as it should.
On the broken site, I disabled various plugins a group at a time until the standard Captcha was being displayed on registration, eventually narrowing it down to a single plugin.

For other Hikashop site owners, both Hika and Joomla Captcha can be enabled.
As long as Joomla's is used on registration you don't get the errors I was seeing on authentication.

Thank you for your assistance and patience.

Sure, I was going to name names but was unfamiliar with etiquette.

The plugin causing the problem was "Offlajn Dojo Loader", a remnant from a product that was "uninstalled".
Seems uninstalling a product only kinda-sorta uninstalls.

Lesson Learned:
The site doesn't yet get a lot of traffic, still in development - but this was an important lesson to do product evaluation on an environment you don't care about.