Application does not contain `com.mikepenz.iconics.Iconics$IconicsBuilder` as referenced in main-dex-list
## About this issue
- library version "com.mikepenz:iconics-core:3.2.5" and "com.mikepenz:iconics-views:3.2.5"
- gradle build tools: "com.android.tools.build:gradle:3.6.3"
- support version: "androidx.appcompat:appcompat:1.1.0"
- Android Studio 3.6.3
- Android SDK 10
- multidex enabled in accordance with [manual](https://developer.android.com/studio/build/multidex)

Large enough application, which uses Androic Iconics

Actually error happens during launching of application can't inflate layout XML, with `IconicsButton`, which is basically smth like:
        
      <RelativeLayout
                android:id="@+id/loginLayout"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="horizontal">

                <com.mikepenz.iconics.view.IconicsButton   <! line #100 -->
                    android:id="@+id/loginButton"
                    style="@style/NarrowDialogStyle.Button"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_alignParentEnd="true"
                    android:layout_alignParentRight="true"
                    android:layout_alignParentTop="true"
                    android:minWidth="0dp"
                    android:text="{gmi_long_arrow_right}"
                    android:textSize="@dimen/increased_text_size"
                    android:textStyle="bold" />

Throwing exception:

>android.view.InflateException: Binary XML file line #100: Binary XML file line #100: Error inflating class <unknown>

Which has origin as of:

>java.lang.ClassNotFoundException: Didn't find class "com.mikepenz.iconics.Iconics$IconicsBuilder" on path: DexPathList[....

Also I have noticed that during build there's warning:

> Task :app:mergeDexRelease
AGPBI: {"kind":"warning","text":"Application does not contain `com.mikepenz.iconics.Iconics$IconicsBuilder` as referenced in main-dex-list.","sources":[{}],"tool":"D8"}

Have tried all possible ways to overcome bug: cache clean, restart, rebuild, playing with 

     multiDexKeepFile file('multidex-config.txt')
     multiDexKeepProguard file('multidex-config.pro')

Useless. Desperately looking for help

P.S. Can't use latest versions since too many code need to rewritten and can't also use previous `support` versions (not androidx)