16 bit mode on software upgrad

This is controlled by the fixture type. Check the details on exactly how you patched your fixtures. You might also want to see if you loaded a show file from years ago. A fixture profile exists both in the console and in a show file. If the old 8 bit version got brought in you might have accidentally loaded it.

Apparently the problem is something else. I loaded my show that I was using last week and the fixtures are having the same issues. Is there another reason that this might be occurring? I am using 5 different types of LED instruments and it is only 1 particular the that is having the issue. I am using a profile for IRGBWS.

It's possibly in the fixture or the profile not matching the fixture any longer. It would really help if you could provide some details about this fixture so we aren't guessing quite so much.

DMX refresh rate is about 44 Hz which can cause noticeable steps if the fixture isn't doing some sort of smoothing. Do the fixtures have different modes or dimming profiles? Maybe it got changed to something more responsive.

The other thing that could cause you grief is RDM which may be enabled, but the symptoms are usually random flickers instead of steppy dimming.

Also: DMX output through a 3rd party node, ETC gateway or DMX ports at the back of the console?

Also: DMX output through a 3rd party node, ETC gateway or DMX ports at the back of the console?