Cannot resolve symbol Theme in styles xml Android Studio

Since today, Android Studio can't find the AppCompat themes in styles.xml, but for example AppCompatActivity in code does get recognized. My Android Studio version is 2.2.2, Build #AI-145.3360264

I already tried upgrading to the latest build tools, compile sdk (25) version etc. but it didn't fix the problem.

At the moment I have installed the following (from sdk manager):

android api: 19 and 23
sdk platform tools: 25.0.1
sdk tools: 25.2.3
build-tools: 23.0.2 and 25.0.1
support repository: 40
google repository: 39

and a few others, that shouldn't be necessary to list here.

build.gradle of app:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 23
    buildToolsVersion '25.0.1'
    defaultConfig {
        applicationId "xxx.xxxxxxxx.xxxxxxxxx" //not the real applicationId
        minSdkVersion 14
        targetSdkVersion 19
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled true
            shrinkResources true
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
        debug {

        }
    }
}

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    compile files('libs/RootTools.jar')
    compile 'com.android.support:support-v4:23.+'
    compile 'com.android.support:support-v13:23.+'
    compile 'com.android.support:appcompat-v7:23.+'
    compile 'com.android.support:design:23.+'
    compile 'com.android.support:cardview-v7:23.+'
    compile 'com.android.support.constraint:constraint-layout:1.0.0-beta4'
    compile 'de.hdodenhof:circleimageview:2.1.0'
}