Do the following:
1. Insert new track
2. Put JS:Tone Generator on it
3. Enable envelope for the Wet Mix slider
4. Set the envelop point shapes to Fast End
5. Insert an envelope point at an arbitrary place say 30 seconds or so away from the first point
6. Raise that inserted envelope point to +6 dB
What happens:
The envelope curve gets a hard knee where it passes 0 dB.
What I expected:
A smooth curve with a slow beginning and fast end.
The top envelope curve here shows the result:
The bottom envelope in the figure above shows what happens when the envelop points are set to Slow Start/End. The knee occurs also in that case where the envelope passes 0 dB.
More detail here
https://forum.cockos.com/showthread.php?t=215959