Not working on some devices

Hello,

I have installed and set up the plugin and for the most part it is great.

However, upon a focus group test of the site sending a message in the chat bot didn’t go through to Facebook. Since then we’ve tested the bot using all different devices to try and rule out the issue but it seems very random.

I have a suspision it’s linked to the plugin not asking whether to ‘Continue as a Guest or Log into Facebook.’ It prompts this question on devices (mostly desktops) that work, but when it doesn’t ask the question, it doesn’t go through to Facebook.

The devices it does not work on that we know of are:
Samsung Galaxy S10, Samsung Galaxy S9, Google Pixel 3

It’s worth noting, we’ve tried all these phones in both Chrome browser and their built in browser (Samsung Internet for example).

What’s going on and how do we fix it?

The page I need help with: [log in to see the link]