Cannot Upload Files When Using Cloudflare Proxy

I’ve been having troubles uploading to my Pydio Cells server when using Cloudflare’s proxy. When looking in the network tab, it gives me a 413 error, despite the fact there’s no upload size limit on my reverse proxy.

I thought for a LONG while that it was some subtle issue with my reverse proxy, as I was able to upload when connected locally, but not through my domain. However, I later learned this wasn’t the case when I set the DNS record to be direct instead of proxied, and then magically it started working.

I doubt this is an issue with Cells itself, but if anyone else uses Cells with Cloudflare and has experienced similar troubles, your input would be much appreciated!

Cells version: Pydio Cells Home Edition 4.4.0 (02218f0a100cdc10c932e57c3bac9923bd799df1) linux/arm
OS: DietPi v9.2.1
Database: MariaDB Ver 15.1