Android studio。難読化したリリースビルドを内部テストでインストールすると、アプリを開く時に落ちてしまいます。

内部テストのリリース前レポートによると、

FATAL EXCEPTION: main

java.lang.VerifyError: Verifier rejected class c.a.a.e: void c.a.a.e.a() failed to verify: void c.a.a.e.a(): [0x3F] cannot access instance field c.d.b.a.f.e.z c.d.b.a.f.e.h.b from object of type Reference: java.lang.Object (declaration of 'c.a.a.e' appears in base.apk)

と出ていました。

minifyEnabled true/shrinkResources = true をminifyEnabled falseにしてリリースするとアプリを開くことが出来ました。

aabをリリースビルドで作成した後のBuild Outputを見ると、

> Task :app:minifyReleaseWithR8
AGPBI: {"kind":"warning","text":"Missing class: io.reactivex.ObservableOnSubscribe","sources":[{}],"tool":"R8"}
AGPBI: {"kind":"warning","text":"Missing class: io.reactivex.Scheduler","sources":[{}],"tool":"R8"}
AGPBI: {"kind":"warning","text":"Missing class: io.reactivex.FlowableOnSubscribe","sources":[{}],"tool":"R8"}
AGPBI: {"kind":"warning","text":"Missing class: io.reactivex.disposables.Disposable","sources":[{}],"tool":"R8"}
AGPBI: {"kind":"warning","text":"Missing class: java.lang.instrument.ClassFileTransformer","sources":[{}],"tool":"R8"}
AGPBI: {"kind":"warning","text":"Missing class: io.reactivex.Scheduler$Worker","sources":[{}],"tool":"R8"}
AGPBI: {"kind":"warning","text":"Missing class: sun.misc.SignalHandler","sources":[{}],"tool":"R8"}
Missing class: io.reactivex.ObservableOnSubscribe

Missing class: io.reactivex.Scheduler

Missing class: io.reactivex.FlowableOnSubscribe

Missing class: io.reactivex.disposables.Disposable

Missing class: java.lang.instrument.ClassFileTransformer

Missing class: io.reactivex.Scheduler$Worker

Missing class: sun.misc.SignalHandler

> Task :app:kaptGenerateStubsReleaseKotlin
w: Runtime JAR files in the classpath should have the same version. These files were found in the classpath:
    C:/〇〇〇/〇〇〇/.gradle/caches/transforms-2/files-2.1/d736dcc68833822a7a6d16e8b5de464c/jetified-kotlin-stdlib-jdk7-1.3.72.jar (version 1.3)
    C:/〇〇〇/〇〇〇/.gradle/caches/transforms-2/files-2.1/5d20f75f81f277f032bb67dc540b8a06/jetified-kotlin-stdlib-1.5.10.jar (version 1.5)
    C:/〇〇〇/〇〇〇/.gradle/caches/transforms-2/files-2.1/753220b7db004c0ac8ffe23f3dad9aad/jetified-kotlin-stdlib-common-1.5.10.jar (version 1.5)
w: Some runtime JAR files in the classpath have an incompatible version. Consider removing them from the classpath
w: Runtime JAR files in the classpath should have the same version. These files were found in the classpath:

> Task :app:compileReleaseKotlin
w: Runtime JAR files in the classpath should have the same version. These files were found in the classpath:
    C:/〇〇〇/〇〇〇/.gradle/caches/transforms-2/files-2.1/d736dcc68833822a7a6d16e8b5de464c/jetified-kotlin-stdlib-jdk7-1.3.72.jar (version 1.3)
    C:/〇〇〇/〇〇〇/.gradle/caches/transforms-2/files-2.1/5d20f75f81f277f032bb67dc540b8a06/jetified-kotlin-stdlib-1.5.10.jar (version 1.5)
    C:/〇〇〇/〇〇〇/.gradle/caches/transforms-2/files-2.1/753220b7db004c0ac8ffe23f3dad9aad/jetified-kotlin-stdlib-common-1.5.10.jar (version 1.5)
w: Some runtime JAR files in the classpath have an incompatible version. Consider removing them from the classpath
w: Runtime JAR files in the classpath should have the same version. These files were found in the classpath:

とありました。調べてみましたが、解決方法が分からず困っております。分かる方がいらっしゃれば教えて頂けると幸いです。よろしくお願い致します。

追記:

buildTypes {
     

        debug{
            minifyEnabled true
            shrinkResources = true
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }

を追加して実機テストするとアプリが動作しました。難読化が原因でアプリが開かないのかと思っていたのですが、これはどこに問題があると考えればよいのでしょうか？