Integrating Slack with Boards Redirects to Wrong Account

Hi everyone, I’ve been trying to integrate my boards with my Slack account. I am a developer for other small businesses, so I’ve been a guest and admin on many accounts other than mine. The problem I’m having is anytime I try to connect the two, I am automatically redirected to an OLD client’s account, regardless of “switching account”, changing the domain URL, removing from google memory. I’m at a loss. Anyone else run into this? I’ve tried it both ways, from Slack app and from TO Slack. Same issue.