Potty training in apartment

I have a 8 month old chihuahua pitbull mix. Potty training has been going pretty well. I live on the 4th floor of an apartment and the beginning of potty training was rough. She doesn’t like going potty in the dirt/mulch and the only grass area in my complex is super muddy and is not the easiest to get to. I got a roll of sod and made a potty patch on my deck, it was a game changer. I started off leaving the door open when I was out there with here and then eventually trained her to use bells. She was doing really good, she just had this habit that I didn’t think was that big of an issue until now. She doesn’t like to pee and poop all in one go… she will go pee, insist on coming inside and then a few minutes later ring the bells to go back out to finish up.

Now here is the issue… the potty patch needed to be replaced (it was a little overdue and she didn’t want to go potty on it anymore ) so I threw it out and just planned on walking her downstairs until I can get a new one. She stays with my mom while I’m at work and that’s what she does with my mom so I didn’t think it would be an issue. I take her outside first thing in the morning, when she’s first let out of the crate, or whatever she shows us she needs to go but most of the time she will only pee when I take her out. Then when we get back up stairs she’ll either ring the bells just a few minutes later or just poop inside. I’ve tried waiting 20-40 minutes outside with her because I know she has to poop and she doesn’t care. She still will want to go back upstairs just to ring the bells to come back down not even 5 minutes later. How do I help her break this habit?