I experienced this today in 8.5.
Never had a problem in 8.0.
I tried restarting 8.5, but every time I wrote volume automation. I tried the outputs of Groove Agent SE as well as a Group drum track. At first I thought it was a Groove Agent bug, so tried doing it with the group fader, but same problem. As soon as I clicked the red “w” to stop writing automation, the track would be silent.
I opened the same project in 8.0.3 and was able to write automation and play it back fine. I did not save the project in 8.0.3.
I then opened the same project in 8.5 and now it is writing and playing back automation fine. I saved the project in 8.5, re-opened it and automation is still playing back OK.
I hope the bug doesn’t come back for me, but if it does, I’ll try opening the project in 8.0.3 and then re-opening it in 8.5.
Hoe that helps someone.
Rich