I was thinking about some kind of useful S&V drill with ball machine. Somethings like ros and S&V just needs tons of reps against a variety of players.
But try this:
Set ball machine up to simulate the ros at a service box location the best you can. So let's say wide deuce for example. A good slice to the corner means opponent is hitting ros in alley, or further wide. Set the ball machine on line with ros spot and volley (bh, fh) location you want reps on around your service line. Yes ... sometimes you might close inside of service line, but being able to hit good volleys to targets from the service line is a S&V staple. Actually ... practice some a little deeper than service line also. I think you want the ball to clear low over the net ... because that's what a good player is going to do against S&V players. I would bh slice low to various spots all day to S&V ... good S&V feast off of high balls. You might have to experiment with setting ball machine way deep ... I put mine against back fence, high speed, low to try and replicate ros. Not same as facing a real serve ... but any 2hbh ros reps I could get helped in my case.
S&V is a rhythm thing ... so what you did hitting a serve and than going through the motions/movement/footwork is probably the best you can do by yourself. But you have a natural serve, move in good ... that will come playing matches. Probably half of S&V is reaction muscle memory ... you pick up early you can hustle and really close ... or it's one to take deeper.
So ... try just working on the reaction/movement part without/after the serve. Since you can't really time footwork/split step with all machine, just get ready in no man's land ...center or faded to sideline a bit for deuce wide reps. Have ball machine feed deuce wide line dtl ... maybe start way inside sideline for your early reps. My thinking is be experimenting with ball machine depth and speed, and your start location ... you should be able to replicate that final part of moving to ros and hitting your volley to intended spots (cones
). Recover to spot at net depending on where you hit your volley ... mind muscle memory.
I think I could set this up ... and the test would be do you end up hitting low volleys (say no higher than a little above net level) from the service line ... all in rhythm. Maybe don't pick a very windy day for first experiment.