How to reproduce:
1. Open attached project ("AddressablesBug.zip")
2. Open "Sample Scene"
3. Build Addressables Asset via Window > Asset Management > Addressables > Build > Build Player Content
4. Use Build > BUG REPRO menu
5. Open Project Folder > Versions > Windows > Fa****.exe
~ Inspect output_log.txt in LocalLow > Abra*** > AddressableBuildBug, it says "Addressable loaded" ~
6. Switch platform to OSX
7. Build Addressables Asset
8. Use Build > BUG REPRO menu
9. Open before mentioned .exe from the same Windows folder
~ Inspect output_log.txt in LocalLow, it says: ~
" (Filename: C:\buildslave\unity\build\Runtime/Export/Debug.bindings.h Line: 45)

Exception encountered in operation UnityEngine.AddressableAssets.Initialization.InitializationOperation, result='', status='Succeeded' - Chain<TextAsset,IResourceLocator>: ChainOperation of Type: UnityEngine.TextAsset failed because dependent operation failed
Dependency Exception

(Filename: C:\buildslave\unity\build\Runtime/Export/Debug.bindings.h Line: 45)

NullReferenceException: Object reference not set to an instance of an object
at LocalisationManager+<LoadSupportedLanguages>d__10.MoveNext () [0x0005f] in <effe8c3f99fb415a854743c4aa5f223e>:0
at UnityEngine.SetupCoroutine.InvokeMoveNext (System.Collections.IEnumerator enumerator, System.IntPtr returnValueAddress) [0x00027] in <883f8ae328204c6d92119e8df47d79f6>:0 "

Expected result: Addressables load up after switching platform
Actual result: Addressables break when you build them after switching platform

Reproducible with - 2020.1.0a6, 2019.3.0b5, 2019.2.7f2, 2018.4.10f1 (Addressables 1.1.5 - 1.2.4)
Could not test with - 2017.4.32f1 (No packman)