When the plant is weak and roots are bad, the cure can be very recalcitrant. Here is a new soft yellowish leaf oc C. skinneri with tip dieback caused by Ca-deficiency. The other leaf of this bifoliate species is already lost, and both leaves of last years bulb as well.
The other plant is C. labiata. Roots are bad, with nearly no new root growth. Last years bulb lost its leaf quickly. This years bulb is stunted.