No luck at all. Dtraces have narrowed it down to a problem with some of our Amazon buckets. For some reason, EV looks through all of the Amazon buckets and is generating an error when it gets to specific buckets. Problem is with the creation date, apparently. I deleted one bucket thinking that would be the fix, but it just got stuck on the next bucket and generated an error. The buckets were just fine with EV 10. EV 11 has been nothing but problems.
Here's the dtrace...
<ListAllMyBucketsResult xmlns="http://"><Owner><ID>debf44a1e3678957bf09b37389b15bf3a69f5a180f178848eb9a7bfdad1818f1</ID><DisplayName>master</DisplayName></Owner><Buckets>
<Bucket><Name>1Cloudstore</Name><CreationDate>2013-10-30T13:24:28.000Z</CreationDate></Bucket>
<Bucket><Name>2Cloudstore</Name><CreationDate>2013-10-30T13:28:12.000Z</CreationDate></Bucket>
<Bucket><Name>3Cloudstore</Name><CreationDate>2013-10-30T13:26:31.000Z</CreationDate></Bucket>
<Bucket><Name>CloudberryBackup</Name><CreationDate>2013-10-24T16:27:35.000Z</CreationDate></Bucket>
<Bucket><Name>1Backup</Name><CreationDate>2016-04-25T16:04:05.000Z</CreationDate></Bucket>
<Bucket><Name>2</Name><CreationDate>2011-06-06T22:40:09.000Z</CreationDate></Bucket>
<Bucket><Name>4Cloudstore</Name><CreationDate>2013-10-30T13:29:46.000Z</CreationDate></Bucket>
<Bucket><Name>5Cloudstore</Name><CreationDate>2013-10-30T13:¸¹ òçÍ
It then fails:
293 11:48:35.072 [3260] (StorageManagement) <17724> EV:M OST Streamer: [TID:19324] [Plugin] amazon:9B71D57D4617254EA4A371C2757B4E74: Invalid bucket name
294 11:48:35.072 [3260] (StorageManagement) <17724> EV:M OST Streamer: [TID:19324] OST API sts_create_lsu() failed with error: 2060001 - 'one or more invalid arguments'.