It seems their update makes it hide and then show its own window on maximize.
You can see this if you watch the taskbar as you maximize the window as you will see one taskbar button slide out as another one slides in.
Unfortunately hiding a window is deemed to have left a group because some apps like TickTick itself also hide themselves when you click close.
Having looked into it we can stop it leaving the group but it will forget its location on screen when restored if it is the active window, but thats probably as good as it is going to get.
