PayPal Standard Sandbox Mode Not Working in v4.6

Seems to be the same problem in v4.6 when trying to test using Sandbox mode as with v4.5
https://www.nopcommerce.com/en/boards/topic/94370/plugin-paypalstandard-response-handler-400-bad-request-nop-version-450

Log level: Error
Short message: Error 400. Bad request
Full message:
Customer: Guest
Page URL: https://mydomain.com/Plugins/PaymentPayPalStandard/PDTHandler?PayerID=MZ4YSYN2UYCK4
Referrer URL: https://www.sandbox.paypal.com/

Request seems to come in as a Guest - dont know if that is an issue

Hi Andrew,

Thanks a lot for reporting. We'll check it out soon - https://github.com/nopSolutions/nopCommerce/issues/6503

I cannot reproduce this error.
On my PayPal sandbox account, payment and redirecting customer to the store happens correctly both with a regular and anonymous checkout.
I even tried setting "Nop.Customer" cookie as Expired in the browser before returning (based on this comment), but even in this case the redirect is completed and the order is confirmed, just a new guest record is created.
No idea how else to get this error.
Does the error reproduce in all browsers?

Btw, I see PDT URL with the query parameter "PayerID" in your log, in my case the parameters are different (e.g. "cm", "tx"). Make sure you configured the plugin correctly.