Export issue - significant volume drop in one group channel, depending on export start time

I’ve been using Cubase Pro 10 for probably 4 years now and have never had this issue before. When I export this one particular project from the start, one of my prominent group channels (an electric bass in a very dense mix) is significantly lower possibly even muted for the entire project in my export. If I start the export a few minutes into the 40 min long project - this channel exports just fine. I am really baffled by this. I tried playing with my automation and plugin settings and cannot find anything that has helped.

I just got a new desktop, so I’m hoping this problem doesn’t follow me to the new computer, but I would still like to know what the hell is going on and what I might do to address it, should I encounter it again.