I feel she was involved.
I'm going to have to go with Occam on this one. The theory with the simplest explanation/fewest new assumptions is usually the correct one.
I feel she was involved, too, but I had never looked at it this way. There are lots of reports, confirmed and unconfirmed, about what went on the day Kyron went missing and after, all of them point to Terri's guilt but only one report (Terri is not a POI or a suspect) points to her innocence.
Report: Terri was the last person to be seen with Kyron and the last time he was seen was with her.
Assumption: An unseen person was the last person with Kyron.
Report: Terri failed two LDT's and walked out of another.
Assumption: She had some reason other than lying for failing the LDT's.
Report: Terri's cell phone pinged near Sauvie Island, though she claimed to be elsewhere.
Assumption: These pings are erroneous.
Report: Terri claimed to need the truck that day to pick up Kyron's project, but she did not pick it up after all.
Assumption: She did not claim that, she was confused, or she had a good reason for changing her plan.
Report: Kyron's teacher and others believed Kyron had an appointment on June 4th.
Assumption: The teacher misunderstood what Terri told her.
Report: Terri did not contest the R.O. or the divorce and has not fought for custody or visitation with her daughter. She has taken no step that would mean she'd have to speak under oath. She is not speaking to LE.
Assumption: She is afraid of being railroaded by LE.
Well, anyway, on and on. But what I don't see in this case are reports of anyone seeing Terri exiting the schoolgrounds alone, Terri shopping and running errands, Terri mentioning her daughter's earache at the time, someone actually seeing Terri at the gym on June 4th, Terri clearing up her timeline for June 4th, Kyron indeed having an appointment for a later Friday, Kyron with someone else after being seen with Terri, etc.
That we haven't seen reports of any of these things doesn't mean they didn't happen, but why would nothing concrete that has come out point away from Terri?