Renaming "EnderIO-1.10.2-3.1.183.jar" to "BEnderIO-1.10.2-3.1.183.jar" did not cause any error messages to be displayed upon starting the game.
I had 6 Powered Spawners, all in my mob grinder room, and all have been inactive anyway (switched off via Redstone) for more than a week. I removed them all anyway. I used only one at a time, for different mobs.
I'm now running and will "soak test" and let you know what happens.
Thank you for your help and patience!
PS: I don't know if this has any significance, but I noticed that my Cursed Earth/Diamond Spikes mobdrop generator slows down dramatically (but does not stop completely) when I am near bedrock ±7 chunks away. It works normally if I'm at bedrock in the same chunk as the mobdrop generator, or if I'm on the surface ±7 chunks away. The generator is fully within a chunk, which is chunkloaded. (Drops are collected in an Ender Chest for teleporting into RefStrg. Evidence for the slowdown is via an Ender Pouch.)