2checkout inline popup box not appear

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Hello guys.

I'm using joomla 3.9.1 with VM 3.4.2

I noticed after updating my VM that the checkout method through 2CHECKOUT plugin is not working properly.

The issue starts when customer tried to make checkout then the inline popup box appear then immediately disappear again.

I went to the website and I tried to do checkout step by step then I realized this issue.

Any recommendations to solve this issue please ?

my store is here  https://bit.ly/2RGHnUD