SOS: Rot and tissue collapse on Rlc. Ports of Paradise.

[BrassavolaStars]

Hello all,

I was in my greenhouse today when I noticed significant issues with this plant. The leaves are falling, there is tissue collapse on the leaves, and a pseudo bulb is mushy at the leaf joint. Much of the leaf damage is to the underside only.

What do I do? Is it black rot? Sunburn? Cold damage? Virus? The greenhouse got down to the lower 40s in the spot where it was but nothing else seems impacted. I have fixed the heater now so it won’t get cold again. It was also in an area not protect well by the shade cloth also. It is also a relatively new plant. What should I do?