Agave cultivation help

[kak tus]

Some of my Agaves are losing their leaves (e.g. blackening from the tips, yellowing) and refuses to grow new leaves. These are my A. nizandensis, A. utahensis, and A. americana (guessing for this one). I suspect overpotting was the cause but I found upon unpotting them that the roots seem to be growing well and filling the whole pot (see pic for A. utahensis). I have tried different watering frequencies (weekly, biweekly) to no avail. I have had success with A. potatorum, A. pumila so I'm quite perplexed why the the other Agaves are not doing well. I will try to repot them in smaller pots but I will appreciate any advice.

[kak tus]

Pics attached

[Hallow]

The bottom one looks good. What do the roots look like on the top one?

[kak tus]

The roots of the top one looked good and growing too. I took the photograph after trimming them. I guess could there be an explanation for healthy growing roots but sickly growth above ground?