How are you measuring pH?
It's likely your meter isn't up to measuring that high of a pH, if you have a cheap meter. Also, the probe will get damaged by strong lye solution.
If the bark isn't present in the mixture, it's not necessary to leave the alkaline soup 'to work' for any length of time as deprotonation of dissolved DMT cations is practically instantaneous given a high enough pH.
As a last resort, you might want to try pressure-cooking the bark, if you still have it. 1kg is rather a lot to basify in one go so I can sort of understand your approach.
Incidentally, what colour was the tea after the acid cook but before adding the lye?
“There is a way of manipulating matter and energy so as to produce what modern scientists call 'a field of force'. The field acts on the observer and puts him in a privileged position vis-à-vis the universe. From this position he has access to the realities which are ordinarily hidden from us by time and space, matter and energy. This is what we call the Great Work."
― Jacques Bergier, quoting Fulcanelli