Flutter/Android Studio代码自动补全失效问题求助

数月前将Flutter升级至3.x版本、Android Studio从4.x升级至2021.x版本后，代码自动补全功能出现异常：仅能提示当前文件或已显式导入文件中的内容，无法自动导入外部库及项目内自定义类，需手动查找包路径导入。未开启省电模式，已按照相关建议清理以下缓存及目录：

Gradle (Windows: user/.gradle)
Pub cache (Windows: user/appdata/local/pub)
Android Studio
    Windows: 
        user/.android
        user/appdata/local/google/androidstudioX
            caches
            compiler
            compiler-server
            conversion
            frameworks
IntelliJ (Project Path ./.idea)
Build Path (Project Path ./build)

flutter doctor检测结果： #

[√] Flutter (Channel stable, 3.3.7, on Microsoft Windows [Version 10.0.19045.2251], locale de-DE)
    • Flutter version 3.3.7 on channel stable at E:\Android\Flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision e99c9c7cd9 (4 weeks ago), 2022-11-01 16:59:00 -0700
    • Engine revision 857bd6b74c
    • Dart version 2.18.4
    • DevTools version 2.15.0

[√] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    • Android SDK at E:\Android\sdk
    • Platform android-33, build-tools 30.0.3
    • ANDROID_HOME = E:\Android\sdk
    • Java binary at: E:\Android\Android Studio 2021.3.1 RC 1\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 11.0.13+0-b1751.21-8125866)
    • All Android licenses accepted.

[√] Chrome - develop for the web
    • Chrome at C:\Program Files (x86)\Google\Chrome\Application\chrome.exe

[X] Visual Studio - develop for Windows
    X Visual Studio not installed; this is necessary for Windows development.
      Download at https://visualstudio.microsoft.com/downloads/.
      Please install the \"Desktop development with C++\" workload, including all of its default components

[√] Android Studio (version 2021.3)
    • Android Studio at E:\Android\Android Studio 2021.3.1 RC 1
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 11.0.13+0-b1751.21-8125866)

[√] Connected device (3 available)
    • Windows (desktop) • windows • windows-x64    • Microsoft Windows [Version 10.0.19045.2251]
    • Chrome (web)      • chrome  • web-javascript • Google Chrome 107.0.5304.107
    • Edge (web)        • edge    • web-javascript • Microsoft Edge 103.0.1264.44
    ! Device emulator-5554 is not authorized.
      You might need to check your device for an authorization dialog.

[√] HTTP Host Availability
    • All required HTTP hosts are available

! Doctor found issues in 1 category.

补充说明： #

• 旧版本项目中该功能正常。
• 当前项目lib目录包含超1000个文件，是否因项目过大导致？
• 在安装了Flutter/Dart插件的纯IntelliJ中该功能正常。

内容的提问来源于stack exchange，提问作者S-Man