Rescue dog will pee/poop outside then go inside soon after

Hello! We adopted a 1 1/2 yr old German Sherpard/Husky mix in August to be buddies with our 3 yr old Cattle Dog. She spent 6 mo at the shelter and was on a farm before hand, and she was not potty trained. She is pretty smart and caught on to basic training easily. The one thing we cant seem to shake is peeing/pooping in the house. We take them both out frequently for at least 15 minutes. They will run around and play, do their business, then come back inside. We praise and give treats outside. We go on walks. She is fed the recommended amount of food. If she goes inside, we use an enzyme cleaner to clean it up. She will poop and pee outside. We take her inside and within 10-15 minutes sometimes she will poop/pee again. We dont scold her for it as she is usually sneaky when she does it. Do we continue what we are currently doing or is there something else we can do? If she doesnt poop? We will kennel her then take her out in 30 mins or so. I do think the scent could still be there, so we are planning to replace the carpets this winter (saving up still) with hard flooring. I appreciate the time and any advice given!