JPA Named Query Returning Empty Array when it Shouldn't - spring-boot

Question

I am trying to query the last 5 digits of a number field from an Oracle DB within a Springboot/JPA Repository.
In Oracle, the following query works:
Select * FROM DP1_Attachments Where trim(substr(dp1_submit_date_dp1_number, -5, 5)) = [a-five-digit-number]
I have tried implementing the following:
ENTITY:
#IdClass(CompositeKey.class)
public class DP1Attachments {
#Id
private Integer attachmentsFolder;
#Id
private Integer attachmentNumber;
private Integer dp1SubmitDateDp1Number;
private String attachmentName;
private Integer attachmentSize;
private String attachmentType;
#JsonFormat(pattern = "MM/dd/yyyy HH:mm")
private LocalDateTime attachmentDate;
private String attachmentBy;
private Integer attachmentByUsersId;
private String attachmentActive;
private String modifiedBy;
private Integer modifiedByUsersId;
#JsonFormat(pattern = "MM/dd/yyyy HH:mm")
private LocalDateTime modifiedDate;
REPOSITORY
#Query("SELECT a FROM DP1Attachments a WHERE trim(substring(a.dp1SubmitDateDp1Number, -5, 5)) = :dp1Number")
List<DP1Attachments> queryByDp1SubmitDateDp1Number(#Param("dp1Number") String dp1Number);
}
SERVICE
public List<DP1Attachments> getAttachmentsList (String dp1Number){
return attachmentsRepository.queryByDp1SubmitDateDp1Number(dp1Number);
}
CONTROLLER
public ResponseEntity<?> getAttachmentsInFolder (#PathVariable String attachmentFolder){
List<DP1Attachments>files = attachmentsService.getAttachmentsList(attachmentFolder);
return new ResponseEntity<>(files, HttpStatus.OK);
}
The query runs but returns an empty array.
I also tried changing the substring to a LIKE statement:
#Query("SELECT a FROM DP1Attachments a WHERE TO_CHAR(a.dp1SubmitDateDp1Number) like :dp1Number")
List<DP1Attachments> queryByDp1SubmitDateDp1Number(#Param("dp1Number") String dp1Number);
And the service changed to :
public List<DP1Attachments> getAttachmentsList (String dp1Number){
return attachmentsRepository.queryByDp1SubmitDateDp1Number("%" + dp1Number);
}
This also runs w/o errors but returns an empty array.