Brassavola nodosa with brown areas on leaves

[mrs.TF]

Hello there,
I have two pots with brassavola nodosa..
They seem to be healthy, but this year they didn't bloom..
There is something going on with their leaves, some of them have brownish areas, some of them whitish areas..

These areas have been there for a long time, and plants seem to be healthy, leaves are green, and i see new little ones, roots are growing too..

I have looked on this forum, and on internet, but i could not find anything relevant..
Any idea what this is?

Thank you very much.