I have the same issue, pretty much.
My office mate likes to bring her drink from breakfast and lunch back to finish. Once done she rattles the ice and eats it. I don’t hear the ‘crunch crunch’ but I do hear the ‘rattle rattle’ every 30 seconds for about two hours (she orders extra ice). It’s starting to drive me insane. I am so glad to find I am not alone.
I have started putting one ear bud in my ear on that side and turning on easy listening music on youtube. Still sometimes I hear it. In that case I turn on a small desk fan for the white noise.
I know (or hope) it isn’t malicious on her part. But I’m about to go nuts!