The first thing to try is to restart and see if it happens again. Restarting can solve a lot of problems. That said, I had a similar problem in Mojave with Safari (the captcha screen went blank). I filed a bug report in my Developer account with Apple. They were very prompt in replying and asked for several more pieces of information. The next update to Safari fixed it. I don't know if this applies anymore, but you could try it. Another tack is to phone Tech Support at 800-275-2273. I have found them to be very helpful.
Jon
macOS 11.7.10, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365
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