json.type.invalid error

[PaulS3090]

I am using the standard wordpress plugin for Constant Contact 1.10.1.  This a very simple form requiring the email addr, first and last names and only allowing join of a single list but this fails with debug logging below. I initially ran into a bug involving the plugin not populating the "Associated List" properly but did the resync work around to fix it. When I run it from my web site, it appears to work (to the user) and displays the "Success Message" but the user isn't added to my contact list. Instead I get the error below.  Is this a well known bug? The parser seems to complain about the lists not being a valid type but my simple understanding of the JSON shows it as Array which is an allowed type.  Help?

[2021-03-21 17:52:48] API.INFO: Contact set to be created ["Extra information",[{"form":"Join Our Newsletter"}]] []
[2021-03-21 17:52:48] API.INFO: ConstantContact_API::add_contact:527 - json.type.invalid - #/lists: Value is of a disallowed type. Allowed types are: Array, Null. [] []
[2021-03-21 17:52:48] API.INFO: Submitted contact data ["Extra information",[{"email___3c59495a3edf2d27cd20fc1987544522":{"key":"email","val":"***@xylem.com"},"email":"***@xylem.com","first_name___7e7a6eef7e0a3734f39d6757b27d474b":{"key":"first_name","val":"PJ"},"last_name___86b6d953df0fd1bff8e02cde526c2b3c":{"key":"last_name","val":"Sang"},"lists___be1f5d4d2510bc1e5729aa31aea09e83":{"key":"lists","val":"Array"},"list":["1979379054"]}]] []

[PaulS3090]

This is still not working and I called the customer support and they suggested I do what I had already done (reconnect, sync...) and if that does not work to post here. Help!!!??

[Courtney_E]

Thank you for reaching out to Constant Contact API Developer Support, and for your patience. My team is here to assist outside software developers with questions about building into Constant Contact's API.

It looks like you've already spoken with our customer support team in greater detail regarding this issue with the Constant Contact WordPress Plugin and we referred you to post your question and debug logs directly on the WordPress plugin forum to receive further assistance from support engineers who work directly with the plugin developers.

https://wordpress.org/support/plugin/constant-contact-forms/

In the event that you are still experiencing this issue, and based on what troubleshooting has already been completed, one more thing I’d recommend trying is creating a completely new list in your Constant Contact account, syncing your lists again in the WordPress plugin, and then connecting the form to the new list.

[PaulS3090]

I've had no luck resolving the issue. Your customer support suggested I post here and you can see what feedback i've received so far.

[Courtney_E]

Thanks for your reply. I have reopened your support case regarding this issue and a specialist will be reaching out directly to follow up regarding the Constant Contact WordPress Integration. If you have any further questions, or do not receive a response within 4 business days, please feel free to contact our support team at 866-289-2101 and reference case #28235111.