Sister doesn't acknowledge gifts

I've gifted my sister plenty of things and she often doesn't acknowledge receiving them or say thanks. I wasn't going to get them any gifts this year, but they randomly gave us an anniversary gift and my husband is quite generous, so we gave them a box of gifts. We didn't get any thanks, we liked/didn't like the gifts, nothing. I feel disappointed and hurt. I know gifts are meant to be given with no expectations but it's polite to at least send a quick thanks for the gifts! How can I address this? I told my husband gift giving will not continue!

UPDATE: she called and very monotonously said "thanks for the gifts." It was the strangest way to say thanks. No excitement, no enthusiasm, and it was seriously a box full of stuff and I gifted them my old KitchenAid mixer too!!! It's not like I got lavish gifts in return. She got my daughter an outfit, my husband a shirt, and I got slippers and earrings. Again, she's done this before with either no acknowledgement or something a day later with no enthusiasm. I'm wondering if I bring it up and ask if they didn't like them?? Hey husband also didn't say thanks and we got him a ton of stuff. Nothing in return (he randomly gifted my husband a gift for our anniversary so my sister got me something too). Just fucking jerks honestly. Entitled. I swear, no gifts in 2025. Leaving the pettiness behind.