Hi @peter35 , I asked the same question when I first got the 4th axis upgrade last week. They said that the extra DRO still in development. You should have an "A" axis displayed in the Machine Coordinates window to get some idea of the current angular position but thats all they have for now. I've been shopping for a decent Rotary Table but have not settled on one yet.... What type of 4th axis table did you get?
I have used Mach 3 for the last 10 years myself. I still use it on my scratch built CNC router but I am enjoying my new MASSO. That sounds like a cool DIY 4th axis option... I probably should look into that as well. I have a couple leftover Nema 34s still in the box that could work. Hopefully they can get the A axis DRO up and running soon.