Size picker works in one language, but not the other

[StarSnib]

Hi all, I'm dealing with a weird issue that I can't seem to solve. 

Our store (veyia.com) is running Prestige with basically no code changes and languages English (default) and German. We have a simple size picker, default from the theme. See here to try for yourself. The issue is as follows:

- When the store language is set to English (default), the size picker works fine. The URL changes with the appended variant ID as expected.

- When the language is set to German, the size swatches are clickable, but the URL does not change and the console throws an error for theme.js: 

Uncaught TypeError: Cannot read properties of undefined (reading 'id')
at VariantPicker.selectVariant (theme.js?v=xxx)
at VariantPicker.onOptionChanged_fn (theme.js?v=xxx)

Theme.js has never been modified. 

Could you help me out? I am absolutely out of ideas.

Thank you!

[StarSnib · Accepted solution]

Solved it by recreating each affected product. Tedious and lost all sales stats, but at least it works again :0