Cache that this LEGO trackable was in went missing sometime in early 2020 and was replaced 6/2020, so either this TB went missing along with the cache or one of the many finders between its 2019 placement and the cache's loss took the TB but didn't officially check it out.
TO, try contacting especially the first couple of finders after the TB was left there - one was particularly new and may not have recognized it as a trackable item.