Why does Firefox freeze on a security interaction with Amazon?

  It is now affecting my purchases on Amazon.  I'm asked to provide a security code from my bank to complete the purchase. The code is initially accepted, but quickly the purchase is rejected by Amazon. Both Amazon and my bank said that there were no blocks on my account.
  I subsequently went to Safari, where I have no problems whatsoever with Amazon. Amazon has not asked me for a bank code to domplete the purchase.
  I think the problem is in my Settings, but it all looks okay. Cookies are cleared. Suggestions are appreciated. Thanks

Firefox has been my default browser on Mac IOS for several years. I update Firefox regularly, the last being several days ago. I've recently had problems with Firefox freezing as I sometimes manually log-in to Amazon. All other tabs are affected. I have to quit, reopen. It is now affecting my purchases on Amazon. I'm asked to provide a security code from my bank to complete the purchase. The code is initially accepted, but quickly the purchase is rejected by Amazon. Both Amazon and my bank said that there were no blocks on my account. I subsequently went to Safari, where I have no problems whatsoever with Amazon. Amazon has not asked me for a bank code to domplete the purchase. I think the problem is in my Settings, but it all looks okay. Cookies are cleared. Suggestions are appreciated. Thanks