It sounds like you may have already done all of the following, but just in case, here are the usual steps to take. It won’t be perfect, and you may have to get support involved, but usually the best place to start is the events log for each of the specific devices involved:
If that didn’t answer the question, you can look at the full logs:
And if that still didn’t clear it up, the next step is to contact support. If you use the email option, make sure you tell them that you give them permission to look at your account and give them the day and time of when the weird stuff happened, as well as the specific devices involved. That way they can get right to work on it rather than having to come back to you for that information before they start.