Did you get this resolved? It can be for many different reasons and some of those reasons will resolve on their own (Perhaps a network issue etc.).
If you still have the issue, please can you let us know what it shows in the dashboard for each hashboard? Are all 3 boards hashing? If it shows one of more of the hashboards as “abnormal” are all the chips hashing on that board? If you click onto the green/red square to the right of each board in the dashboard you can see an overview of each chip.
If they are red (Abnormal), the only way to troubleshoot this would be to take a look at the logs. If you are happy to share the logs feel free to do so, however this is upto you.
Note that Bitmain do have a support forum too if you would feel more comfortable with them directly. Their support/tech team is quite helpful.
Hope this helps,