oracle11gr2用rownum在分页时执行计划出现异常,无结果集返回？

近期更换了数据库版本,把oracle10g替换成11g2r
出现了一个问题,一些原本可以运行的分页sql数据获取没有了结果集反馈,测试后发现产生的条件是:
-1,select中包含rownum
-2.where条件中包含两个区间一致的查询日期条件比如
AND l.be_starttime >= trunc(SYSDATE, 'yy')
AND l.be_starttime >= to_date('2019-08-01', 'yyyy-mm-dd')
两个条件同时存在时会在执行计划中出现一个   2 - filter(NULL IS NOT NULL)
具体实例sql:

SELECT l.activityarr,ROWNUM
          FROM crm_lead l
         WHERE l.isactive = 'Y'
           AND l.ad_org_id = 1000000
           AND l.docstatus = 'I'
           AND l.be_starttime >= trunc(SYSDATE, 'yy')
           AND l.be_starttime >= to_date('2019-08-01', 'yyyy-mm-dd');

该sql的执行计划:

Plan hash value: 2923278655
 
--------------------------------------------------------------------------------------------------
| Id  | Operation             | Name     | Rows  | Bytes | Cost (%CPU)| Time     | Pstart| Pstop |
--------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT      |          |     1 |    18 |     0   (0)|          |       |       |
|   1 |  COUNT                |          |       |       |            |          |       |       |
|*  2 |   FILTER              |          |       |       |            |          |       |       |
|   3 |    PARTITION RANGE ALL|          |  3887 | 69966 |  7956   (1)| 00:01:36 |     1 |     4 |
|*  4 |     TABLE ACCESS FULL | CRM_LEAD |  3887 | 69966 |  7956   (1)| 00:01:36 |     1 |     4 |
--------------------------------------------------------------------------------------------------
 
Predicate Information (identified by operation id):
---------------------------------------------------
 
   2 - filter(NULL IS NOT NULL)
   4 - filter("L"."DOCSTATUS"=U'I' AND "L"."AD_ORG_ID"=1000000 AND "L"."ISACTIVE"='Y')

求助这个问题能怎么处理?具体产生原因是什么呢?