This bug has been in the test server for some time now.
It went live with last night's maintenance.
http://forum.tsotesting.com/threads/...work-correctly
Better description:
The first time you make a full stack of something in the Barracks and the Provisions House (I usually click on the right side of the slide area), the slide bar will only want to go to 19 instead of 25.
The next stacks will go to 25 like they should until you refresh or otherwise reload the game.
A minor annoyance compounded by how long it has existed and then moved to the live server.
(reading other posts, other bugs got implemented too.)