When uploading a world on your Realm on PS4 that is slightly larger (around 190 MB), it will not successfully replace the world currently in the realm. When uploading a larger one (ex. 270 MB) it will not begin the export process and softlocks, even with a sufficient internet connection or upload speed.

Expected Result:
Any world smaller than 5 GB should be able to upload to the Realm and replace the world currently in the Realm.

Actual Result:
Depending on the size of the file, the world may successfully export but will not save on the Realm, or with bigger files it may not begin the export at all. Additionally, when in the world options, the "Play on Realms" button will cause the game to freeze if played on a larger file.

This is a problem for people who want a better world of theirs on a Realm for others to see 24/7, and other devices connected to the same account wouldn't be able to access it from the Realm. Realms are a feature on PS4 that have been long awaited and this is a fundamental flaw that should be addressed as soon as possible.