Cursor blinks on ios

Ionic Framework ionic-v3
1

Cursor blinks when I typing on Input or Textarea
How to fix this issue?

ezgif-2-bca791b44bc4
see video

I use cordova-plugin-ionic-webview 4.0.0. and platform version is ios@4.4.0
cli packages: (/Users/----/.nvm/versions/node/v8.11.1/lib/node_modules)

@ionic/cli-utils  : 1.19.2
ionic (Ionic CLI) : 3.20.0

global packages:

cordova (Cordova CLI) : 8.1.2 (cordova-lib@8.1.1)

local packages:

@ionic/app-scripts : 3.2.2
Cordova Platforms  : android 6.3.0 ios 4.4.0
Ionic Framework    : ionic-angular 3.9.2

System:

Android SDK Tools : 26.1.1
ios-deploy        : 1.9.4 
Node              : v8.11.1
npm               : 5.6.0 
OS                : macOS
Xcode             : Xcode 10.1 Build version 10B61

Environment Variables:

ANDROID_HOME : /Users/mingyu/Library/Android/sdk

Misc:

backend : pro