Stuck in a config loop

I set a small website selling a virtual product, which replaced a WIX site. I installed WooCommerce, and did some partial configuration (before I knew better) under Payments | PayPal Standard, mainly the Live API User/Password (from the WIX site). The payment method is not currently enabled. I then installed WooCommerce Paypal Payments, and activated it. Under Payments page I click “Complete setup” and enter my login creds. In the PayPal dashboard a new Rest API app was created.

PayPal says I’m done and I return to the site, but I’m forever at the ‘Complete setup’ stage and asked to log back into PayPal to complete my setup. Clicking the button again briefly opens a ‘PayPal’ page with an up-arrow link beside it – when I click the link it shows these errors:

Error retrieving plugin details.
Error retrieving PayPal Settings details.
Error retrieving onboarding details.

I’ve tried clearing cache, disabling/enabling the plugin, and uninstalling/reinstalling the plugin. Tho the PayPal Standard payment method is inactive I can go into ‘Manage’ and I updated the API creds to match what the PayPal app is using. I did try blanking the API creds on this page, but when I saved the change it took the site offline completely. I restored a current db backup and now I’m back to where I started.

Not sure if this is helpful, but when I click the up-arrow link mentioned above with Chrome dev tools open, the Console shows these:

event name: mb_ramp_config_loaded, fptiParams: {“msg”:”MB ramp config is loaded”}
partner.js:1
event name: mb_no_partner_found, fptiParams: {“msg”:”PayPal URL does not contain the partner ID during setup”}
partner.js:1
event name: mb_use_old_script, fptiParams: {“msg”:”Partner is not yet ramped to zoid, loading old script”}

I’m using WooCommerce v9.8.5 and WooCommerce PayPal Payments v3.0.5.

I’ve done a lot of web searching, but no joy – this is killing me. Any suggestions, or additional detail you require?

Thanks in advance – Brian