Hi, thanks for sharing your experience.
I applied from Argentina with a Canadian sponsor and just got the email of the application going to Mexico as well.
I’m glad to read we are not the only one.
I had a similar problem with my wife. We tried Safari and Chrome and nothing was working. For me I tried with my iPhone through Safari and it worked in my first try. I don’t know if it was luck or what but I recommend you trying it.
Hope my experience to be helpful.