I am using Poll SCM:

*/5 * * * *

I think these logs are describing the issue very clearly:

Build #23 (Oct 25, 2018 11:25:08 AM)

Revision: 114936 Changes some code rearrange and refactoring - Jenkins test (detail) by XXX

Build #24 (Oct 25, 2018 11:30:08 AM)

Revision: 114936 No changes.

Build #25 (Oct 25, 2018 11:35:08 AM)

Revision: 114936 No changes.

Build #26 (Oct 25, 2018 11:40:08 AM)

Revision: 114941 Changes one more commit; (detail) by XXX