I can access addons.thunderbird.net with Firefox without any problems or being asked to "verify you are human by completing the action below.", yet when I try to access it from Thunderbird's add-ons manager, I am asked to complete the captcha, which after about 30 seconds of "Verifying you are human. This may take a few seconds." goes back to "verify you are human by completing the action below." I tried troubleshoot mode to no avail, I am not using a VPN or anything like that.