[dtr]

Thanks for the advise,

though retest failed. The described measure puts the failure forward to the point, where the captcha isn't even shown. Chrome browser plugin is counting up a red number in the lower right and remarkably makes an effort to bring up the captcha on click but fails.
Android reports the presence of one or more captchas, brings up the captcha loading dialog but removes it before something is shown to be solved.

Both remain in announcement of those captchas to be waiting. Other captchas are shown correctly and the solution is sent.