Yellow Shrivelling Pseudobulbs on Oncidium

[mBluebear]

Hi,
My Oncidium had that problem before. Turned out that there're many tiny snails hid behind the roots.
I repotted the orchid, removed al the snails in the roots, and put snail pellets on the top of the medium. Not sure if there're any snails left.

You should repot it and check for any pets hide in the roots.
Good luck