You mentioned this in your original post a couple of months ago, but I think it was overlooked in the responses. As @Larsen says, a corrupt SD card resulting from the sudden power loss may be the root issue. If you don’t have a recent backup, I’d suggest starting a fresh installation and then importing your configuration data. Otherwise, you might just keep running into new issues all stemming from that initial corruption.
I also recommend a UPS. You just need a small one that can keep your RPi running long enough to shut down smoothly, with a USB port for Network UPS Tools.
You can also get onboard battery backups for RPis. I recently picked up a couple of Red Reactors on Kickstarter. They arrived in February, but I haven’t found time to install them.