Ok so while this seems to be a good explanation, I created a world in 20w20b and updated to 20w21a, and the Temple spawning still worked.
I have Intel HD Graphics 5000 drivers. I have seen similar problems like mine, but all of them say, "After I changed this setting...." Or "Once the new launcher appeared......" Yet my problem somehow developed during the time my pc was shut down.
I have had Minecraft for a while, then this problem happened: java.lang.IllegalStateException: failed to create a child event loop when I try to play a world. Any help?
same with me for all 4 farms. seems across the board nether fortresses and pillagers are fixed, but witch and monuments are not.