Logged in users can not order

[bryanearl]

VM VERSION: 3.8.4
JOOMLA VERSION: 3.9.19

I have been struggling with a problem since the last two VM version updates with user reporting they are getting an error when trying to check out "Invalid data entered. Please ensure the credit card number, CVV code and expiration date are entered correctly."

We have two payment methods enabled, authorize.net and PayPal. It doesn't matter which method is selected, the error happens wither way. For that matter:

1. If they chose PayPal, it never redirects for payment, it only displays the thank you message and the error (while never creating an order entry in the system)... It's like the order never happened.
2. If they choose authorize.net, it's not checking the fields as it should... In other words, they don't even need to enter a credit card number. If they click submit, it gives the error and the thank you page (while never creating an order entry in the system)... It's like the order never happened.

On an important side note, this does not happen EVERY TIME!

1. If a user is logged in to their account, the above happens nearly every time.
2. If a user is NOT logged in, the order process tends to work properly most of the time.

Please help! This is driving me up a wall and the client is not happy, as they are missing out on orders.

ADDED:

I happened to look at the VM "Shopper Groups" settings (because being logged in has something to do with this), and I found that there appears to be a problem with the "Default Shopper Group" and "Guest Shopper Group" (please see attached screenshots)...  The fields are not translating properly and display is messed up. Any ideas of if this is realted or what may be going on?

[GJC Web Design]

not an attempt to help with the problem but just to say the lang file en-GB.com_virtuemart_shoppers.ini that contains the translations for things like COM_VIRTUEMART_SHOPPERGROUP_DEFAULT_TIP is not being loaded on the SG page.
This is why they are not translated but I don't think this will have anything to do with the problem u describe

[bryanearl]

What would the fix for that be? How can I get it to load the language file as it should?

[GJC Web Design]

Have reported it to the devs, in the meantime if u think its important just make some Joomla lang overrides