Edit: "Moving it in OnUpdate (and skipping the first call) resolve the issue." skipping the first OnUpdate call doesn't seem necessary.

Found what I think to be a related issue (not completely sure about that though). I got a crash when trying to access a transform.position in a JobComponentSystem onCreate method. Moving it in OnUpdate (and skipping the first call) resolve the issue.

I use some preview packages and not LTS unity version and the workaround is simple, but may these info can help.

+ unity 2020.1.0b1
+ manifest.json {
"dependencies": {
"com.havok.physics": "0.1.1-preview",
"com.unity.2d.sprite": "1.0.0",
"com.unity.2d.tilemap": "1.0.0",
"com.unity.ads": "3.4.4",
"com.unity.analytics": "3.3.5",
"com.unity.animation.rigging": "0.2.3-preview",
"com.unity.burst": "1.1.2",
"com.unity.collab-proxy": "1.3.7",
"com.unity.entities": "0.1.0-preview",
"com.unity.ext.nunit": "1.0.0",
"com.unity.ide.rider": "2.0.2",
"com.unity.ide.visualstudio": "2.0.0",
"com.unity.ide.vscode": "1.1.4",
"com.unity.jobs": "0.1.1-preview",
"com.unity.mathematics": "1.1.0",
"com.unity.multiplayer-hlapi": "1.0.4",
"com.unity.physics": "0.2.4-preview",
"com.unity.platforms.macos": "0.1.3-preview",
"com.unity.purchasing": "2.0.6",
"com.unity.rendering.hybrid": "0.1.1-preview",
"com.unity.test-framework": "1.1.13",
"com.unity.textmeshpro": "3.0.0-preview.1",
"com.unity.timeline": "1.2.6",
"com.unity.ugui": "1.0.0",
"com.unity.xr.legacyinputhelpers": "2.0.2",
"com.unity.modules.ai": "1.0.0",
"com.unity.modules.androidjni": "1.0.0",
"com.unity.modules.animation": "1.0.0",
"com.unity.modules.assetbundle": "1.0.0",
"com.unity.modules.audio": "1.0.0",
"com.unity.modules.cloth": "1.0.0",
"com.unity.modules.director": "1.0.0",
"com.unity.modules.imageconversion": "1.0.0",
"com.unity.modules.imgui": "1.0.0",
"com.unity.modules.jsonserialize": "1.0.0",
"com.unity.modules.particlesystem": "1.0.0",
"com.unity.modules.physics": "1.0.0",
"com.unity.modules.physics2d": "1.0.0",
"com.unity.modules.screencapture": "1.0.0",
"com.unity.modules.terrain": "1.0.0",
"com.unity.modules.terrainphysics": "1.0.0",
"com.unity.modules.tilemap": "1.0.0",
"com.unity.modules.ui": "1.0.0",
"com.unity.modules.uielements": "1.0.0",
"com.unity.modules.umbra": "1.0.0",
"com.unity.modules.unityanalytics": "1.0.0",
"com.unity.modules.unitywebrequest": "1.0.0",
"com.unity.modules.unitywebrequestassetbundle": "1.0.0",
"com.unity.modules.unitywebrequestaudio": "1.0.0",
"com.unity.modules.unitywebrequesttexture": "1.0.0",
"com.unity.modules.unitywebrequestwww": "1.0.0",
"com.unity.modules.vehicles": "1.0.0",
"com.unity.modules.video": "1.0.0",
"com.unity.modules.vr": "1.0.0",
"com.unity.modules.wind": "1.0.0",
"com.unity.modules.xr": "1.0.0"
}
}