I've encountered some flaky behavior with the realm.Subscriptions.WaitForSynchronizationAsync() function in the sync .NET E2E tests here. Basically the issue is that occasionally the test will not properly wait for the download from the server and continue. I've confirmed that the server is sending the correct instructions, so it seems that the client sometimes isn't waiting for those properly. Interestingly, adding a call to realm.SyncSession.WaitForDownloadAsync() after the WaitForSynchronizationAsync() seemed to fix this