To reproduce:

1. Download attached project "OpenGL Native texture.zip" and open in Unity
2. Open "Scene" scene
3. Ensure that OpenGLES Graphics API is set as primary
4. Build for iOS with Development Build checked
5. Deploy the Xcode project to the iOS device
6. Observe that grass texture appear after 100 frames then see the black texture on subsequent appearances

Notes:
- This issue does not reproduce on Windows Standalone, macOS Standalone, and Android (IL2CPP)
- If between Load and Delete, Create and Delete Texture2D in Unity problem is not appearing
- If You create a new texture first and delete old after that problem is not appearing
- Problem appearing only in Development Builds. If it is not checked problem is not appearing
- The plugin works for Metal. In Metal devices problem is not appearing

Tested with:
- iPhone SE, iOS: 11.4.1 - Reproduced
- iPhone 7s Plus, iOS: 12.0 - Reproduced

Reproduced on Unity 2017.4.0f1, 2017.4.14f1, 2018.1.9f2, 2018.2.15f1, 2018.3.0b9 and 2019.1.0a8