one thing that helps in troubleshooting, to keep isolating causatives is eliminate any concern over the cycle, if there is some its manufactured here's why:
-no cycle chart exists for taking longer than 30 days
no ammonia line on any cycle chart takes past 12 days.
you added a known source of ammonia oxidizing bacteria, feed, and has completed the # of days on all cycling charts.
-not one seneye post in history on a benchmarked, calibrated meter shows a cycle taking any longer than a few days to stabilize after dosing, you're at 30.
for cycling to have any play here, we have to be able to find pattern threads to the opposite of above, but we can't. on any forum.
so in the params we test in reefing, this has to be non cycle params if any causing the issue
calcium and magnesium and alk aren't a concern in fish loss posts.
that's a bright open tank, not an oxygen issue
see how it narrows and narrows down to: fallow and quarantine.