Cannot upload experimental world to Realms

Worlds with experiments can no longer be uploaded to Realms, this used to work perfectly fine. There even is a “work in progress” experiments tab on Realms implying that this should just work.

Steps to reproduce

1. Create a local world with one or more experiments enabled.

2. Upload the world to a Realm, through the “Play on Realms” button in the Edit world screen or the “Replace world” button on Realms.

Expected result

The upload initiates and finishes shortly after, with the world playable on the Realm. The enabled experiments still function there.

Observed result

The upload gets stuck at “exporting world” or immediately closes without a warning. There is no way to upload the world to Realms, and since you cannot disable experiments, this is quite problematic for long-term worlds that happened to have an experiment on.

I also noticed that worlds on Realms that already had experiments enabled, just got them disabled, which causes some severe issues and corruption.

Note: I only tested this on Preview