11 month regression?

My 11 month old miniature dachshund has become a barking machine. I understand it is the breed, but it is constant. It is not barking due to a trigger or discomfort, it is demand barking/barking for attention. If he does not have direct attention or a Kong he is barking. It has been increasing the last few months and has become nearly intolerable the last 2 weeks.

We walk for 45 min in the morning then do a short training session when we get home, then the barking begins. We continue short walks and training sessions throughout the day, however, the barking persists.

The crate used to be our safe haven – he would immediately settle in the crate and go to sleep. However, the last two weeks he has started barking in the crate. There has been no change to environment or routine.

We just completed our second puppy training course, this time around focusing on the barking, and after 8 weeks the barking has only gotten worse.

We have tried redirecting with a command – he barks for my attention, I tell him to sit or down, he stops barking for that moment, then starts barking again. Repeat. We have tried ignoring the barking. After a few minutes of barking in your face he will stop, we reward the silence, then he starts barking again. Repeat. If we don’t reward the silence he starts barking again.

I can’t give him my attention or a Kong 24/7 to keep him quiet. Now that he has started barking in the crate we have no “last resort” when he won’t settle down. We live in a townhome so I am concerned this will become an issue with the neighbors if it doesn’t let up.

I am open to any and all advice as I am getting desperate. I am at a total loss and feel like a failure. Thanks in advance.