Overworld gets deleted randomly

[KomplettHacke]

Bug Report

I went through my nether portal back to the overworld and everything in the overworld got deleted: Saved map on journeymap and at my spawnpoint is nothing anymore.
Loaded a backup: No problems the first 3 times but then it happened again

Steps to Reproduce (for bugs)

1. Go through a nether portal?

Logs

• Client/Server Log: https://paste.feed-the-beast.com/view/7f42305f
• Crash Log: There is no crash log. I just closed the game and loaded the backup when the world got deleted

Client Information

• Modpack Version: 1.0.37
• Server/LAN/Single Player: Singleplayer
• Optifine Installed: No
• Shaders Enabled: No