your problems are nothing to do with ph
do not do anything to the rockwool other than making it fully wet
follow these instructions and your cuttings will root without fail
i am giving you help on how to look after the cuttings once they have been taken, i am assuming that you have taken the cuttings correctly
and that you have used some kind of rooting hormone , and that your problems are not with taking the cuttings themselves but making them root once taken
1 make sure your propagator/humidity dome is working correctly ( put a small amount of water in it , place the lid on, put it somewhere warm and wait and see if condensation builds up
2 knowing that your propagator/ humidity dome is now working and producing high humidity by the presence of plenty of condensation inside the dome place the cuttings inside
allow a small amount of water to remain inside the dome ( keep it shallow, no more than 0.5 cm deep but allow it to cover the whole bottom of the dome this remaining water will cause the high humidity .. do not worry about the water being still, it cant become stagnant in the short amount of time that it will remain in the dome (1 week) is fine
3 spray the cuttings with water only, do not spray them anymore than 2 times per week or every 3 days, they do not need spraying, keeping them wet delays rooting
there is enough water at the bottom of the dome to cause high humidity, it is the humidity that stops them from wilting
resist the urge to spray them too often
4 keep the vents of the dome closed for the first 3 days .. you do not need to do anything else at this early stage, just leave them in the dome vents closed
5 after day 3 you can start to open the vents for a few hours each day, do this every day until they root , after the first week in the dome, you can replace the small amount of water at the bottom of the dome with fresh water, .. keep repeating the same process until they root, if you take the lid off for long periods to inspect them give them a little spray before you put the lid back on,
but keep this fussing over them to a minimum , constantly opening the dome to inspect them lowers the humidity,
keep the propagator in a warm place under low lighting 50 watts of florescent light is enough for a small dome
6 you do not need to give the cuttings any food or additives during the rooting process, if you are having issues i would say cut out anything unnecessary as it can do more halm than good, do not use heat mats or a heated dome, these can also fail and cause more harm than good
keep it simple , cuttings will root 100% in 10-14 days
peace