Shipping costs double somehow for primary language

Hi!
I’m just steps away from finalising my woocommerce store, but I’m experiencing some trouble with shipping. I have followed the tutorial on how to add shipping zones and everything goes perfectly well for my secondary language cart and checkout. However, when I look on my primary language cart and checkout pages, the shipping costs get doubled.
I tried disabling all plugins and switching to the default theme, but the problem remains, so it must be in woocommerce. I also switched from Polylang to WPML, because I thought it might have something to do with the way they handle multilingual sites, but that didn’t change a thing either.
I’m really at a loss of what can be the problem. Help would be greatly appreciated.

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