Change of article category changes article publishing dates
From Joomla! Documentation
There is a known issue with datetime fields in Joomla! 3.9.16 when you change the category of an article.
It depends on the setting for parameter "Website Time Zone" in "Global Configuration" whether your Joomla! site is affected or not.
And only if you use custom fields for articles your site is affected.
For example: "Website Time Zone" is set to "Berlin".
Additionaly you have created custom fields for article edit view.
Changing the article category in field "Category" alters silently the time values of ALL date fields in tabulator "Publishing" by +1 hour, sometimes +2 hours; even without saving the article.
This pertains only to Joomla! version(s): 3.9.16
How to fix
- At the moment (Joomla 3.9.16) review of the date fields in tabulator "Publishing" after changing the category if you are in single article view.
- Use Batch process button in articles list view to change the category.
- Update to Joomla 3.9.17 stable as soon as it is released.