Drag and drop for MS Office and PDF files don't work in answers

2020-08-19 10:33:35,959 ERROR [https-jsse-nio2-8443-exec-3] [atlassian.confluence.event.ConfluenceEventDispatcher] run There was an exception thrown trying to dispatch event [com.atlassian.confluence.event.events.content.attachment.AttachmentUpdateEvent[source=com.atlassian.confluence.pages.DefaultAttachmentManager@44464c8b]] from the invoker [SingleParameterMethodListenerInvoker{method=public void com.atlassian.analytics.client.listener.ConfluenceEventListener.onEvent(java.lang.Object), listener=com.atlassian.analytics.client.listener.ConfluenceEventListener@1863b508} (timed)]
 -- referer: https://localhost:8443/c722/questions/1703939/drag-drop-attachment | url: /c722/plugins/drag-and-drop/upload.action | traceId: bceddcb8e094d780 | userName: admin | action: upload
java.lang.RuntimeException: Invalid property 'attachmentContainerUpdated' of bean class [com.atlassian.confluence.event.events.content.attachment.AttachmentUpdateEvent]: Getter for property 'attachmentContainerUpdated' threw exception; nested exception is java.lang.reflect.InvocationTargetException. Listener: com.atlassian.analytics.client.listener.ConfluenceEventListener event: com.atlassian.confluence.event.events.content.attachment.AttachmentUpdateEvent
	at com.atlassian.event.internal.SingleParameterMethodListenerInvoker.invoke(SingleParameterMethodListenerInvoker.java:57)
	at com.atlassian.confluence.event.ConfluenceListenerHandlersConfiguration$TimedListenerInvoker.invoke(ConfluenceListenerHandlersConfiguration.java:96)
	at com.atlassian.confluence.event.ConfluenceEventDispatcher$VCacheRequestContextRunnableFactory$1.lambda$run$0(ConfluenceEventDispatcher.java:93)
.
Caused by: java.lang.NullPointerException
	at com.atlassian.confluence.event.events.content.attachment.GeneralAttachmentUpdateEvent.isAttachmentContainerUpdated(GeneralAttachmentUpdateEvent.java:76)