Unable to shift my transmission out of Park.

This is a problem which occurred once about a month ago and now it appears to have become permanent. When it happened a month ago I just tried it about a hundred times until it worked. Now, I can’t get it to work no matter what I do. I’ve seen another thread which sounded like this issue, but the resolution to that thread was to lengthen the cable for the parking brake, which seems to have required dropping the transmission.

Here’s the issue: I can start the car just fine, but when I go to shift the transmission from Park, I am unable to depress the button on the shift knob. It acts as if the ignition is not in the On position or the brake pedal isn’t depressed, while both of those conditions are met. I’m looking for a solution that is a little more passive than dropping the transmission.

I’ve fiddled with the ignition, pulled up the parking brake and put it down, tried it with the brake up, tried it with the car running and when it’s just in the On position with the car not running. Nothing I do appears to help. Any ideas?