@B4llistic
It did indeed change when
Blue Iris introduced dynamic group layouts. Assuming you haven't messed with your group layouts beyond just rearranging cameras, all you should need to do is find UI3's
Group Settings panel and increase the
Dynamic Group Max Resolution:
In the
UI3 web interface, right click the video and choose
Group Settings:
Adjust the "
Dynamic Group Max Resolution" setting however you like. This number defines the largest
width or height that a group video stream can be. So for example the default value of 1440 means neither the width or height can exceed 1440 pixels.
If you want the group video stream to look as sharp as possible when fullscreened on a 4K television, you'd need to set the "Dynamic Group Max Resolution" number to 3840 or higher (and also choose the "2160p" streaming profile).
Just be aware that higher-resolution group streams require more of your Blue Iris server's CPU time to encode. The default value of 1440 for this setting was chosen because it offers comparable group streaming image quality and CPU usage to what was available by default in older Blue Iris releases. If you were to max out the slider, it is not uncommon for one group stream to use several entire cores of your Blue Iris server's CPU.