I have seen someone else talk about this in this forum, but I have run into the bug where the portals from the Piglin Army sink through the ground after they take direct damage. The only way to remove them is by quitting out of the world and rejoining, otherwise they fall endlessly past the normal world bounds. The mods I am running with Shadows of Abaddon are as follows: Thorium, Calamity, Calamity Music, Split, Spirit mod, FargowiltasSouls, Fargowiltas, FargowiltasSoulsDLC, WMITF, Magic Storage, Wing Slot, AutoTrash, Ancients Awakened, FargowiltasMusic, Boss Checklist, and Vein Miner.