Potty training rescue dog

Hi everyone. I adopted a female rescue about a month ago. She is approximately 3-5 years old and I have no information about her history. I am having so much trouble with house training because she will not eliminate unless she is alone inside. She likes to go on the carpets in my apartment. She will wait for 24+ hours if she needs to. I've been trying the training schedule (~15 mins outside then ~15 mins inside tethered to me) and even when I sit outside with her for an hour or more, she refuses to go.

I'm at a loss for what else to try. I have gotten her to pee while on leash a couple of times at my parent's house and rewarded her with cheese and tons of praise but outside my apartment building is a different story. Any ideas are greatly appreciated!