You either have a possible record level of CYA or something is not right with the test.
And looking at your first few posts, given that you had 10-12 tablets in the pool at all times ... I am guessing the former.
Time to start replacing water. Leave at least a foot in the shallow end, refill, mix and retest. Although honestly, I think I would drain, refill, then drain and refill again before bothering with the test.
And you should order FAS-DPD and CYA reagent refills now so you do not run out.