Well the other Infinity stones may not be disintegrating because of a couple of reasons.
1. Not enough power
The bulk of Scarlet Witch's power was going towards disintegrating the Mind stone on Vision. She probably had to stretch herself thin to thwart Thanos as well at the same time. And even then she was barely keeping at it! It would be reasonable to suffice that the energy was not enough to destroy 4 Infinity stones together. Also, if you noticed she was channeling her energy as a barrier to keep Thanos from reaching Vision and not as a direct source on the stones themselves, as she was doing on the Mind stone.
2. Incompatible energy
If I recollect correctly, Vision at some point during the events of Infinity War comments that an energy whose signature matches the signature of the Mind stone could destroy it. And then he looks towards the Scarlet Witch. I am guessing that Scarlet Witch's energy signature matched only that of the Mind stone. And it also makes sense because initially the Scarlet Witch's power was mind manipulation, telekinesis and hypnosis. So she would have known that she could not destroy the other stones even if she wanted to and thus made no attempt at it.