One thing to note with dynaplugs - they are amazing but you want as much air in the tyre as possible to push against so when you spot a hole that isn’t sealing, get the metal prong thing in it asap to hold air in and possibly to temporarily seal it while you give it a bit more from a pump before you start trying to put the actual plug in. It also helps to determine exactly what angle to push the plug in as you can feel it with the probe and to make sure there isn’t flint or something still in the rubber.