Some SharePoint web parts don’t always show up until the page is refreshed

Additional environment details

• SPFx version: 1.18.2
• React version: 17.0.1
• Fluent UI version: 8.106.4
• Node version: 16.x / 18.x

Issue description

We are experiencing an intermittent rendering issue with an SPFx solution (v1.18.2) containing five custom web parts.

The solution builds successfully and deploys to the App Catalog without errors. All web parts can be added to a modern page as expected. However, the following behavior occurs:

1. When loading the site in a new browser tab (by pasting the site URL and pressing Enter), the top two or three web parts occasionally do not render.
2. If the page is refreshed, the web parts load correctly.
3. If navigating away from the page and then returning, one or more web parts may again be missing.
4. No errors are logged in the browser console, but the web part placeholders are absent from the DOM.

Questions:

1. What are the potential root causes of web parts disappearing intermittently in SPFx 1.18.2 with no console errors?
2. Could unused dependencies (e.g., lucide-react or overlapping icon libraries) impact SPFx bundle loading or rendering?
3. Are there known issues with SPFx 1.18.2, React 17, or Fluent UI v8 in scenarios where multiple custom web parts are loaded on the same page?

Before:

After: