I did a A310 flight from KDEN to KDFW with a pretty straightforward route. After reading your comment and doing my homework, looking at some very interesting cockpit videos on YouTube, and reviewing a fascinating document I came across on google about the A310 autoflight system, the method I took to using the autopilot was as follows:
-Climb in Profile
-Cruise in ALT.HLD
-Descent starting in VS using descent calculators, then eventually changing to LVL/CH before configuring for approach and landing
The V/S Dev showed I was way below the descent path, but at least I hit all of the altitude restrictions properly this time. 😅
One thing I noticed on the descent was that I could not set a pre-set speed in knots in the speed display, and was wondering if this was a bug. Pre-set speed worked fine before departure (setting my V2 and then using Pre-set to select 250 knots). On descent, when the plane was descending in VS and Mach and I attempted to pre-set a speed of 290 knots (so it could capture 290 knots on the descent per the STAR), the Pre-Set button did not light up and the display read 000 knots, spooling the engines down at that point. Clicking the black button to the left of that display returned me to mach, and the engines were revving up again. I ended up just leaving it in Mach speed until 290 knots was indicated, then selected the black button to change Mach to Knots.
Many thanks for your insight and feedback!