Query Returns No Results When Clips Exist

What could cause a Query to return no results when there are clearly clips in its query range? As I understand it, if you have Query Capabilities on the Pool with the Clip(s) in question, then performing a Query operation across a containing date range should always return the ClipID(s). But I've got Clips that are clearly still existing yet which don't return as results from a Query. The really strange thing is that I know Query has worked in the past, since that's how I got this list of ClipIDs in the first place.

Here's an example, straight from JCASScript:

CASScript>capabilities

CASPool Capabilities:           
         Supports Read Operations:     True
         Read Pools:       default,84ba3j94-2ln1-94p2-f8ca-decns48b78z6-5
         Supports Write Operations:    True
         Write Pools:      default,84ba3j94-2ln1-94p2-f8ca-decns48b78z6-5
         Supports Purge Operations:    False
         Purge Pools:     
         Supports Delete Operations:   True
         Delete Pools:     default,84ba3j94-2ln1-94p2-f8ca-decns48b78z6-5
         Supports Exist Operations:    True
         Exist Pools:      default,84ba3j94-2ln1-94p2-f8ca-decns48b78z6-5
         Supports Query Operations:    True
         Query Pools:      default,84ba3j94-2ln1-94p2-f8ca-decns48b78z6-5
         Supports PrivilegedDelete :   False
         PrivilegedDelete Pools:     
         Supports Monitor Operations:  False
         PoolMappings Pools:  
         PoolMappings Profiles:     
         Supports DeletionLogging :    True
         Default Retention Period:     -1
         Blob Naming Scheme:           MD5,MG
         Cluster Mode:                 CE+
         EventBased Retention:         Not Supported
         Retention min-max:            Not Supported
         Retention Hold:               Not Supported
         Retention Hold allowed:       False
         Minimum Fixed Retention:     0
         Maximum Fixed Retention:     -1
         Minimum Variable Retention:  0
         Maximum Variable Retention:  -1

CASScript>query

Performing clip query

Query Expression Properties:
        Start Time: 2003.12.01 00:00:00 GMT
        End Time  : 2004.01.01 00:00:00 GMT
        Type      : EXISTING & DELETED

Number of clips returned:     0
All results returned:         True

CASScript>clipOpen 7OXERNA2P3EM9eQ7LNA2LWENPEN

Clip Properties:
        Name:                example_clip
        Creation Date:       2003.12.09 12:40:43 GMT
        Size:                2055
        Number of Tags:      1
        Number of Blobs:     1
        Retention Class:    
        Retention Seconds:   94608000
        Modified:            False
        EBR Enabled :        False

If anyone knows what could be causing this, I'd really appreciate some input. I am completely baffled at this point. Thanks!