I have had to train Honey to pee and poop on pads because she absolutely will not go outside on a leash. When we pet sit at Barbs, my family or anywhere else she is great and goes in the yard if she is not a leash. Both Hannah and Honey need to be walked everyday because of being in the apartment and no fenced yard, but she still refuses to go outside on a leash. Honey will walk great on the leash, act like she is going to go, tell her to go pee and poo and praised her when she would go by chance, but for 95% of the time will let you stand outside with her for hours at a time and come in and go on the pee pads or floor within two seconds of brining her back in. I have left poop lie around, have taken her out with Hannah and she sees and smells where Hannah goes, and still refuses to go outside on a leash? Rubbing her nose in it does not make a difference either, she could care less.
We feel your pain and frustration; Marley is 1 1/2 now and he'll go pee and poo on leash, but he'll also go in the house. He won't go in his crate. We take him out frequently and have worked on this with clicker training, bells (our older GD Ziggy has successfully been using the bells at the door since he was 10-12 weeks old). I even did umbilical cord training consistently for 3-4 weeks. That was most successful but the time comes to "cut the cord" and once we started giving him more freedom, the occasional accidents started again. Thanks God we have all hardwood floors which are easy to clean, and his poop is pretty firm and easy to pick up. The pee accidents are less frequent. He is a rescue from a puppy mill (we got him at 13 weeks) and I read that many rescues are very difficult to train as their only option is to go in their crate (though he doesn't go there). Running out of ideas and sure wish we could give Marley more freedom with confidence.
Ned had a lot of trouble going while on-leash at the beginning of the summer. We do a lot of RVing and were house breaking him last summer so we didn't notice a problem. We just kept at it this summer and he has finally learned but it is hard for him to let go. He never goes when we take a walk and is just beginning to go when we are at the dog park. Someone suggested that he is "shy" and I do think that is it. He gets distracted when people or dogs go by and he tries to poop right up against a fence (doesn't do this at home). Perhaps your dogs want privacy for doing their business like Ned. If so, try to take them when distractions of people, dogs, vehicles aren't around. Ned is not from a puppy mill so he has no excuse like yours do.
Honey will never go in her crate unless I put her quilt in with her, she will pee on that...go figure on that one. I have now had to pick up their quilts because of her peeing on them. I did have going out on a long leash line at my son's, but since we are in the apartment and we live on the corner of two streets its hard for her not have traffic or distractions. She has no problem going at the dog park, around other dogs or people. She has no problems running around my brother or sisters yards and going with other dogs around. The only thing I can boil it down to is it's the Leash, if she is free to run around like a nut no problem, but with the leash can't and where we live she can't be free, there is no yard and no fencing area to let her run. With Hannah I couldn't have a better dog, never a problem once she got trained at about 16 to 18wks of age, and Love them both so much, but with Honey it's just two little things that blow up to something huge and she can't keep doing this.
Does your apartment have a deck? Maybe you could use that? I think it's the distractions of a busy street that's causing this..if you have no other choice,I would start at square one take her out every 20 minutes, keep her on a tether when you are inside so she can't go off somewhere and potty. When you take her out, give her the length of the leash only to roam around and find a spot, wait 3 minutes, if nothing happens take her in and try again 20 minutes later. Once she is going reliably outside, extend the time to 30 minutes- then 40 etc.
We have steps leading out to a side walk, and parking area...we also have a small patch of grass where they can go, or we drive down to the river area and they can go down there. She has always done her business in the house when a leash is involved, even at my son's where there were no distractions but the yard was not fenced in...so she was on a long leash ...My brothers, sisters have fenced yards and their dogs...she goes outside there and there are a lot distractions around...at Barbs she goes outside with Dunkin and Hannah and goes. I will try tethering her again and going out more with her to see if she will stop this...it's just so fustrating and I don't want the pee pads around..yuck.
Try taking a pee pad out with you. You have successfully trained her to go in the house and now we need to untrain her. Remove the pee pad from inside. Clean all around that area with vinegar to hide the smell. Keep walking her to the pee pad outside. If she's in her crate all day and doesn't pee, you know she needs to go when you get home. Take her out with the pee pad. It may take all night, but she'll eventually have to go. Until she is reliable inside, she just can't be unsupervised. In the crate or tethered to you. You're serious now!