My boyfriend doesn't respond to my nudes

I've been with my boyfriend for 2 years. We have a mentally and physically really healthy relationship. Super open, very loving and we have sex often. I occasionally send him a nude just if I'm feeling sexy and missing him, and he opens them and just doesn't respond. Litterally doesn't say anything. During sex/forplay he obsesses over my body and tells me everything he loves about it, but for some reason he just doesn't respond via pictures now. I don't look any different, and he used to be more into them and would even send some back. Advice??