I didn't arrive home to read your post and test until 11:00 pm last night. My husband cannot test. He's color blind and cannot tell when it turns clear. He added 12 ozs. cal-hypo after I left for work yesterday morning at 5:15 am. I tested at 11:00 pm.
fc 0.5
cc 0
ph between 7.6 and 7.8
alk 90
cya 50

We didn't have any bleach or any stores open at that time of the night so my husband went first thing this morning to buy the bleach. He put the 3 gallons in around 6:00 am. However it could not be tested until I arrived home at 6:00 pm.

fc 9.0
cc 0
ph 7.8
alk 90
I assume the cya is still the same.

Why would it hold the fc reading with bleach but not with cal-hypo? I would say I might have gotten a bad or old batch of cal-hypo but I've been using this 25 lb bucket of cal-hypo since 6/7/1 and did not have a problem holding a chlorine level until now. We started out with dichlor because I couldn't find any cal-hypo, but it was raising my cya too much.