Starting from Content Hub 4.2, migration to React has been initiated. Some pages will still be rendered in Knockout until the transition has been fully implemented. This might cause an issue. The External Component based on a React.js bundle cannot be rendered on a Knockout page. An empty modal window might be displayed instead of the External Component.
Note that you can check whether a page is rendered in Knockout by its ID using this link as an example:
https://tenantHostname/en-us/admin/entitymgmt/entity/{idOfPage}
If the page is rendered in Knockout, you will see the parameter isReact: false in the Data property on the Entity detail page.
To resolve the issue, rewrite the code of the External Component in Knockout and use this component on the Knockout page. Make sure that you revert the version of the External Component with the JS bundle from 3.0 to 1.0, so that you can use the Knockout version of the External Component. To edit the version, access the External Component entity using this link as an example:
https://tenantHostname/en-us/admin/entitymgmt/entity/{idOfExternalComponent}