As world population grows, invasions of nations slow to a halt

Sadly I do not have any screenshots or video of it, I made a connection to something that’s been happening for awhile now, as my worlds reach a massive population (currently only 18,216) invasions on other countries are essentially impossible, no matter how many armies flood the devastated country, the invasion clock doesn’t run and a “cap” is reached. Prior to this however, empires of 6+ nations are extremely slow to invade even one country, struggling for many in-game years before finally taking it over, I currently have my “random events” option off as the nations have no choice but to wipe eachother out or not act on anything at all. It’s something that takes away from the experience of watching the civilizations grow and fall, at some point it all stops and it’s a sense that the history for the world is over. However, I have hope that it can be fixed, even with it possibly taking some time, I am patient and still enjoy WorldBox very greatly!