To address this issue, you can try the following steps:

    Check Theme Compatibility:

    Ensure that the theme you've installed is compatible with Odoo version 16. Some themes might not be updated to support the latest Odoo versions, leading to compatibility issues.

    Clear Browser Cache:

    Clear your browser cache to ensure that you are loading the latest version of the theme's frontend assets.

    Check for Theme Updates:

    If the theme is from the Odoo App Store or another source, check for updates to the theme. If there's a newer version that claims compatibility with Odoo 16, consider updating to that version.

    Review the Theme Documentation:

    Check the theme documentation for any specific installation or configuration steps. The documentation may provide insights into addressing common issues.

    Contact the Theme Developer:

    If the issue persists, consider reaching out to the theme developer or support team. They may be aware of the problem and could provide guidance or an updated version of the theme.

    Inspect Browser Console:

    Open your browser's developer tools (usually by pressing F12) and go to the "Console" tab. Look for additional error messages or warnings that may provide more details about the problem.

    Temporary Workaround:

    If you are comfortable with JavaScript and the issue is critical, you might consider temporarily disabling or commenting out the problematic part of the theme's JavaScript code as a workaround. However, keep in mind that modifying the theme's code directly might have implications, and it's preferable to work with the theme developer to find a proper solution.