I've seen other instances of people asking about their assemblies no longer show up because SolidWorks glitched and the assembly is outside of the bounding box. I found that in my case, this is happening because my Front and Top planes have increased substantially in size (while I was working on it). The kicker is, SW won't let me change the size of them. I've tried dragging the corners, and they don't move. I've also tried right clicking the planes and selecting "re-size", with no changes. I've checked for any features that could have changed in size that would pull the planes out that far, but have found nothing.
I'm hoping for a simple solution because this is a huge assembly, and my last resort would be starting from scratch and re-inserting/mating all the assemblies which would be a huge damper on time.
The first photo is for reference of how stretched the planes are. The red circle is where my assembly is located. The second photo is zoomed partially in to where the red circle is for reference.