Use a recently maintained version of DSLV, which compiles correctly with newer Gradles.

build.gradle

@@ -33,6 +33,7 @@ allprojects {
     repositories {
         mavenCentral()
         google()
+        maven { url 'https://jitpack.io' }
     }
 }
 

dependencies.gradle

@@ -31,7 +31,7 @@ ext.versions = [
         twitterSerial        : "0.1.6",
         koin                 : "2.2.2",
         picasso              : "2.71828",
-        sortListView         : "1.0",
+        sortListView         : "1.0.1",
 
         junit4               : "4.13.2",
         junit5               : "5.7.1",
@@ -90,7 +90,7 @@ ext.other = [
         dexter             : "com.karumi:dexter:$versions.dexter",
         timber             : "com.jakewharton.timber:timber:$versions.timber",
         fastScroll         : "com.simplecityapps:recyclerview-fastscroll:$versions.fastScroll",
-        sortListView       : "asia.ivity.android:drag-sort-listview:$versions.sortListView",
+        sortListView       : "com.github.tzugen:drag-sort-listview:$versions.sortListView",
 ]
 
 ext.testing = [

ultrasonic/src/main/res/layout/current_playlist.xml

@@ -27,6 +27,7 @@
         app:remove_mode="flingRemove"
         app:fling_handle_id="@+id/song_drag"
         app:drag_start_mode="onMove"
-        app:float_background_color="?attr/color_background" />
+        app:float_background_color="?attr/color_background"
+        app:float_alpha="0.7" />
 
 </LinearLayout>