What's wrong with AssetBundles Build Pipeline & Conditional Compilation?

Hello there!
Here's an interesting situation:

I have a project with a modular structure. I've added the Mobile Notifications package to implement local push notifications. I have a module that implements iOS logic, and a module with implementation for Android. Modules swapped using conditional compilation depending on the target platform.

It looks like t$$anonymous$$s:

 #if UNITY_EDITOR
     injectionBinder.Bind<INotificationsController().To<NotificationsControllerMockup>();
 #elif UNITY_ANDROID
     injectionBinder.Bind<INotificationsController().To<NotificationsControllerAndroid>();
 #elif UNITY_IOS
     injectionBinder.Bind<INotificationsController().To<NotificationsControllerIOS>();
 #endif

Everyt$$anonymous$$ng work perfectly until I build AssetBundles:

 BuildPipeline.BuildAssetBundles(AssetBundlesDirectory, options, target);

I get several errors like t$$anonymous$$s:

 error CS0234: The type or namespace name 'Notifications' does not exist in the namespace 'Unity' (are you missing an assembly reference?)

So the conditional compilation works fine in the Editor, but for AssetBundles somet$$anonymous$$ng goes wrong. I thought the t$$anonymous$$ng is in usings, so I put controller implementations in separate namespaces:

 #if UNITY_EDITOR
   injectionBinder.Bind<INotificationsController>().To<Modules.Notifications.Impl.NotificationsControllerMockup>();
 #elif UNITY_ANDROID
   injectionBinder.Bind<INotificationsController>().To<Modules.Notifications.Impl.Android.NotificationsControllerAndroid>();
 #elif UNITY_IOS
   injectionBinder.Bind<INotificationsController>().To<Modules.Notifications.Impl.IOS.NotificationsControllerIOS>();
 #endif

Doesn't work.

The only t$$anonymous$$ng that works is when I wrap the whole class body with #if:

 #if UNITY_ANDROID
 
 using System;
 using Modules.Config.Api;
 using Modules.Notifications.Api;
 using Unity.Notifications.Android;
 
 namespace Modules.Notifications.Impl.Android
 {
     public sealed class NotificationsControllerAndroid : INotificationsController
     {
         ...
     }
 }
 #endif

Any idea how it's resolvable besides wrapping the whole NotificationsControllerAndroid bonus in a #if? Many thanks!