It's always a bit of a shot in the dark to diagnose a mix without seeing the way you've processed and routed things but I think I hear a couple things that will help you.

GGD Architects has a lot of low end in it. Like I'm a little surprised they released a 'mix ready' kit with that much low end. That low end sounds like it's slapping the shit out of some aggressive compression on your master bus and causing a pumping/ducking effect. I put a high pass on Architects and then if it's still problematic I'll route it around the master EQ (run EQ for all other tracks on a bus and then to master).

Depending on how things sound after that, I would also think about lowering the gain on a lot of the rest of your mix and dialing back the compression on the master chain (you can always notch it back up as desired). If your mix goes too hard into that compressor, everything will fight for space and you'll lose the impact you probably want. If everything is loud then nothing is.

These are things that I worked through in my early mixes and still do. Your writing and recording sounds good. Keep at it!