Yes and yes.
I had a valve that sunk post op into the canal...leaving the hole in my skin without any reason to stay open. They tried to fold the skin over onto itself to open up the hole, to inject it with cortisone and a few other tricks (z plasty)...none worked in my case, I needed to have the valve pulled up and out the skin to block it open.
The 3xs that they tried to fix it I had to keep the tube in for a minimum of a week...to avoid having the sutures rip out or irritate the zone.
If you have no problem getting the tube in and past the stoma then you might want to just tape something in to keep it open (I tried a baby pacifier for a while)...it didn't go deep enough to pop open the vavle..so I wore it comfortably for quite a while.
Good luck and let us know what exactly they do to your stoma.
Sharon