I don't have a decent repro case, because I haven't wanted to tempt fate. but here's my story.

My t4 ensorcell on my runestaff was weird. My t3 had been "only if horribly unlucky" (even off of a workshop, I think), but my t4 was coming up 'needs a miracle.' 8 hours later I tried again, and it was 'only if horribly unlucky.'
Checklist: I am positive I checked with full health, full spirit, uninjured, wearing the same set of enhancives each time, always in a house workshop.

My t5 has had something similar happen. It was coming up as "needs a miracle" on several attempts last night, and again this evening (again, always with full spirit). Then I took off all my enhancives and tried it in front of the bank while waiting for someone - now I got "more likely than not!" I went back into the workshop, but I did something different this time. When I wear my enhancives, I end up at 10/11 spirit, and I have been speeding things along by using symbol of renewal to get full spirit again. This time I waited to hit 11/11, without the aid of the great spirit Voln and friends. Sure enough, "only if horribly unlucky."

Is there any condition where a player would not have his spirit read correctly for ensorcelling? It seems unlikely, but it's the only plausible cause I can come up with.

>Not sure about ensorcelling.

they don't matter