It is normally that they have gone dormant, but looking at the photos it looks like the growth point is distorted. This can happen and I think it’s due to a mite. If my plants get this I throw them away.
As David said coir is fine but make sure it’s salt free.
Pine bark is great, some of us including me grow almost all my plants in milled pine bark (melcourt) and most cps love it esp Sarracenia and vft.