I'm not too familiar with ASV, but it looks that while your obstructive apneas are under control, your hypopneas are not, even with opening up the settings more. Generally, IPAP is usually what is increased for hypopneas and flow limitions (sometimes EPAP can be helpful depending on the situation). For whatever reason it doesn't seem that your machine is responding very well to events when they happen.
If it were me I would trial a higher PS min - say 4cmh2o. According to the link below (pardon my complete lack of knowledge regarding M.S.), some people with M.S. experience weakness with the breathing muscles and need help with ventilation (especially at night). This is largely done by PS (IPAP - EPAP) because the EPAP keeps your airway open and the IPAP helps your muscles rest by assisting with breathing and getting air in for gas exchange.
Note: I may be completely off track with your actual needs/problems, but it could potentially be helpful and I don't claim to be an expert.
http://www.nationalmssociety.org/Sympto ... g-Problems
For Respironics, their titration guide recommends the following starting point for ASV:
EPAP Min: 4
EPAP Max: 15
PS Min: 0
PS Max: 20
Max IPAP: 25
Rate: Auto
If you experience obstructive apneas: increase EPAP
If you experience central apneas: increase PS max
If you experience an inadequate breathing rate on Auto mode: Set fixed rate of 8 - 10bpm, or 2bpm below spontaneous rate. Then set inspiratory time of 1.5 seconds.
https://www.sleepapnea.com/downloads/10 ... fGuide.pdf