We realized this was the issue when we installed a different maintenance plugin and received the same result. (I’m assuming it was returning a 503 header status as well.)
To correct this issue with our site we had to comment out the response headers. We realize this isn’t ideal but we weren’t able to receive any kind of worthwhile support from FatCow and it’s better than a blank page. Showing a blank page is an incorrect action on FatCow’s part – the 503 header status is appropriate for this implementation.
I’m assuming there is nothing we can do on our end to bypass the blank page other than commenting out the response header. We’re up for any suggestions though!