Taking your suggestion into account, perhaps:
"The Pyrrhonist does not assert that each of the issues about which he suspends judgment is in itself undecidable; rather, he continues to investigate the questions for which he has not as yet found any answer."
It's just a suggestion. What do you think? The sense of this sentence is that if the P. believed that the disagreements are in themselves undecidable, they would think that it is pointless to continue his investigation. But he does not believe that, so he may keep on investigating.
Sextus