I have added Javascript under<script> tag on order page, but it loads only after refreshing the page

Summary:

A custom read-only field “Prepayment Percentage” added on the Purchase Order (PO) page using Page Composer appears only after refreshing the page. When navigating via Overview → Manage Orders → Open PO (SPA navigation), the field does not appear unless the browser is refreshed

Content (please ensure you mask any confidential information):

We have customized the Purchase Order page (Complex Work Purchase Order) using Page Composer (Site layer) to display a calculated field “Prepayment Percentage” under Additional Information.

Requirement

• Display Prepayment Percentage calculated as
  Prepayment Amount / Total * 100
• Field is read-only
• Calculation is UI-based (JavaScript)
• Field should appear immediately when PO page is opened