Problem with terminated site workflows which continue working in Sharepoint Online

Recently we faced with interesting issue in Sharepoint Online: there were several 2013 site workflows on different sub sites which worked this way:

1. Iterate through publishing pages in Pages doclib of the current site and if current date is close to page’s Valid to date, workflow sends reminder email to responsible person
2. Wait 1 day and then repeat iteration through pages

i.e. by itself workflow never ends. However it is possible to terminate workflow from UI: Site contents > Site workflows > click workflow > End workflow (see my previous post Restart site workflows in Sharepoint Online)

We published new version from Sharepoint Designer, ended previous workflow instances from UI and started new instances. And here we found interesting issue: terminated workflow instances continued to work, i.e. they continued to send emails of previous version to the users. In UI their status was displayed as Terminated. At the moment we contacted MS support but if you know about this issue please share it in comments.