SPFx Property Pane Not Opening on Classic Page in SharePoint 2019

[samyTech11]

Target SharePoint environment

SharePoint Server 2019 (on-premise)

What SharePoint development model, framework, SDK or API is this about?

other (enter in the "Additional environment details" area below)

Developer environment

Windows

What browser(s) / client(s) have you tested

• [ ] 💥 Internet Explorer
• [ ] 💥 Microsoft Edge
• [X] 💥 Google Chrome
• [ ] 💥 FireFox
• [ ] 💥 Safari
• [ ] mobile (iOS/iPadOS)
• [ ] mobile (Android)
• [ ] not applicable
• [ ] other (enter in the "Additional environment details" area below)

Additional environment details

Node.js: 8.17.0 gulp@3.9.1 yo@3.1.1 @microsoft/sharepoint-generator@1.10.0 SPFX: 1.4.1

Describe the bug / error

When placing the web part in edit mode on a classic SharePoint 2019 page and clicking the "Configure" button, the property pane fails to open. Instead, it remains in a perpetual state of loading, and no further action can take place.

Steps to reproduce

1. Navigate to the desired web part and initiate the edit mode by selecting "Edit web part".
2. The configuration dialog should appear upon this action.
3. Proceed by clicking the "Configure" button within the dialog.
4. The property pane exhibits persistent loading without displaying the options.

Expected behavior

The property pane should open, allowing the user to change configuration settings for the web part.

[ghost]

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