Phragmiprdium Professor Braem Leaves Turning Brown

[Chani]

Hi all,

I'm pretty new to growing phrags. At this point in time, I'm growing three of them, but only one of them, Professor Braem, has this issue. And it's had this issue pretty much from the get-go. I'm attaching pics (at least I think I am) of the leaves for reference. It almost looks like the leaf cells are dying. I truly don't know what this is. I tried reducing fertilizer, reducing light, and cutting off the affected areas, all to no avail. I also checked the roots and they look fine to me.

Any thoughts? Thank you so much in advance, everyone. You all on Orchidboard are always so helpful