File Uploads Conflicting

When testing several WooCommerce Custom Fields plugins, whenever using a ‘File Upload’ field the checkout process fails with an Ajax spinner and the following…

Uncaught TypeError: o.split is not a function
at HTMLDocument.<anonymous> (woocommerce-boost-sales.min.js:1)
at HTMLDocument.dispatch (jquery.js:1)
at HTMLDocument.r.handle (jquery.js:1)
at Object.trigger (jquery.js:1)
at Function.ajax (jquery.js:1)
at HTMLInputElement.upload_file (thwcfe-public-checkout.min.js:1)
at HTMLInputElement.dispatch (jquery.js:1)
at HTMLInputElement.r.handle (jquery.js:1)