MIL walks away or ignores me when I answer her questions

Whenever my MIL asks me something, usually about my son, my house, how the pregnancy is going, etc., if I actually answer with anything more than a few words, she either walks away while I’m talking (literally), nods and changes the subject to herself when I’m done talking, or if it’s via text she will say ‘sounds good’ or a thumbs up reaction. She has complained to my husband that I’m not open enough with her so I try to give actual answers but I definitely don’t think I’m talking too much. I don’t get why she asks if she’s not interested in the answer. My husband brought it up to her and she got offended that this is my ‘percepton’ and said she doesn’t know how to interact with me then. My husband suggested she just doesn’t know how to be polite but she maintains a job and I don’t see her doing this to anyone else..