Android Admob无法加载广告：0-等待未来TimeoutException时出错，仅限OREO

我在Admob上遇到了一些问题，我不知道为什么，但这只是OREO的问题。若我只在OREO中运行应用程序，在其他版本中运行得很好，我会遇到以下错误

我在谷歌上搜索了很多，但没有找到任何解决方案

10-19 14:02:47.991 3124-12984/? E/Ads: Error waiting for future.
    java.util.concurrent.ExecutionException: java.util.concurrent.TimeoutException
        at com.google.android.gms.ads.internal.util.future.af.get(:com.google.android.gms@14366015@14.3.66 (040300-213742215):18)
        at com.google.android.gms.ads.internal.util.future.g.a(:com.google.android.gms@14366015@14.3.66 (040300-213742215):11)
        at com.google.android.gms.ads.internal.request.service.c.a(:com.google.android.gms@14366015@14.3.66 (040300-213742215):62)
        at com.google.android.gms.ads.internal.request.service.c.a(:com.google.android.gms@14366015@14.3.66 (040300-213742215):169)
        at com.google.android.gms.ads.internal.request.service.f.run(:com.google.android.gms@14366015@14.3.66 (040300-213742215):1)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:458)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
        at java.lang.Thread.run(Thread.java:764)
     Caused by: java.util.concurrent.TimeoutException
        at com.google.android.gms.ads.internal.util.future.m.run(Unknown Source:2)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:458)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:301)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162) 
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636) 
        at java.lang.Thread.run(Thread.java:764) 
10-19 14:02:47.992 26870-26887/com.xxx.xxx W/Ads: There was a problem getting an ad response. ErrorCode: 0
10-19 14:02:47.993 26870-26870/com.xxx.xxx W/Ads: Failed to load ad: 0

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有什么帮助吗？

我只从我的申请中找到了答案

您只需等待至少2-3天。

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今天我检查了3天后，它工作正常，我的代码没有任何变化。

发布你的代码，，，我已经按照文档做了同样的事情，它还显示了较低版本的广告，然后是OREO。