I've been using ChickenChunks on my modded server for a week now.
Last night the server randomly crashed and hasn't worked since. It keeps crashing on startup.
On the Forge forum I got this answer. They told me to report this here.
Here's the crash report:
crash-2020-12-29_22.09.28-server.txt.
Can we fix this ourselves or is this due to a bug with ChickenChunks?

This should be resolved by changes made in Forge to prevent these deadlocks. See: #74

Our server (using the same modpack) has the same issue.
I had left the chunkloader on 0 chunks, but I don't know if this is the cause.

(See #51)

I am also having this issue. At first there wasn't too much of a problem but tried to disable allowOffline in the config but this caused the loaders to not work at all. I then tried to re-enable them but this caused the server to repeatedly deadlock. Now no matter what the setting is, when I log in the server crashes. Please consider adding in a config setting to disable the block for purposes like this.