Dialogue System: Lua code 'return Dialog[thisID].SimStatus ~= "WasDisplayed"' threw exception 'Lookup of field '20' in the table element failed because the table element itself isn't in the table.'
What version of the Dialogue System are you using? Are you using cross-conversation links or running more than one conversation at a time? (Both of these are issues that were addressed in previous versions.)
If this happens with every SimStatus check, have you enabled SimStatus in the Dialogue Manager's Other Settings section?
I use no cross-conversation links and only one conversation at a time.
It might have been the SimStatus. I had it enabled, but somewhere between prefab and scene something could have turned it off. After checking that it is on everywhere, I don't get errors anymore and it seems to work. Sorry for wasting your time.