Steps to reproduce:
1. Download 1122824_repro.zip and open "test" scene
2. Enter play mode
3. Notice that wind effect isn't prewarmed

If the issue isn't reproducible with the attached project
1. Create a new project
2. Add particle system and game object with wind zone component
3. Enable in particle system Prewarm and External Forces module
4. Enter play mode to see that External Forces are correctly prewarmed
5. Close and reopen the project
6. Enter play mode notice that wind effect isn't prewarmed

Expected results: After reopening project wind zone effect is prewarmed on a particle system
Actual results: After reopening project wind zone effect is not prewarmed on a particle system

Reproduced with: 2019.2.0a4, 2019.1.0b2, 2018.3.5f1, 2017.4.20f1

Workaround: removing and re-adding wind zone component fixes the issue.