image and price don't change on variant change on product page

[TrendBlend]

Hello,

when I change my variant using my sticky add to cart app, nothing changes on the product page. The app says it is not happening because of the app since the variant url does change. Can someone please help me with this.

It does show the correct price and image after refreshing but it should display correctly on variant change.

In my app sticky add to cart widget the image and price change correctly. URL: MagCharge – TrendBlend

[Shadab_dev]

Well it means it is changing but changes are not live until page loads. This is a problem from the app. 

[TrendBlend]

The app creators said this: 

Were you able to read our previous email regarding the image on the sticky bar? I’ve noticed the issue, and it seems like the app updates the URL with the correct variant ID, but the theme isn’t updating the variant state.

[Shadab_dev]

May be the app code clashes with some part of the theme code.

[TrendBlend]

Hello, there is no product.liquid file, which file should I put the code in? 

[TrendBlend]

Hello, there is no file such as 'product.liquid'

[TrendBlend]

Hello, I do have a product.json file: Sep 30 4:18 PM - Codeshare. 

But I'm not really sure where to add the code, it gave a lot of errors when a pasted it at the bottom of the file