We are using version 1.3.1 on M2.3.2. However, we have found an issue that the address attributes don't show on the billing checkout page.
Please check and fix it.
The issue just happens on M2.3.2 because the file Magento_Checkout/js/view/billing-address.js default does not work with custom customer attributes.
To solve the issue, we have edited two files
Please check and apply the solution on your site.
If you need any further assistance, please feel free to contact us.
We're more than happy to support you.