Discouraged-Won’t stop chasing

Hi, I have a 6 month old border collie/ black lab mix. She is sweet as can be but hyper as heck. She is a giant lick and just loves everyone and everything. She also chases my cat and I’m starting to get discouraged about it. She came from a home with 2 cats and 3 kids. The previous owners said she was playful but never vicious towards the kids or cats. Starting out she was curious about our cat and might stalk a little but was not bad. I acquired her at around 12-14 weeks old. But several weeks in she started the chase. No matter what I have tried she won’t stop the chase. My husband runs/walks her daily and we bring her to the woods where we let her go nuts and run to her hearts content. I have her in puppy training, I’m following the advice of the trainer and she is picking up every command like it’s nothing but for some reason I just can’t get her to STOP CHASING! We have 3 finished floors in our house. The dog stays on the main floor and the cat goes between the top floor and bottom. Everyone kept saying “the cat will teach her.” Well he hasn’t, and he’s almost 10 with no front claws to defend himself (I didn’t make that decision to declaw, not my cat to start off). I don’t even think she intends to hurt the cat but I can’t trust it and it always turns into utter chaos if the dog manages to corner the cat before I see him come into the room. The cat will dive into our arms with the dog following behind jumping up us. The dog is put in a play yard when I’m not in the room or at home. Is there any hope here? I feel so discouraged that there will never be a day of coexistence.