I am on a world that had forge and on 1.14.4 that was working perfectly fine until I went into creative mode for a while and then tried to switch to survival. As I typed the command it showed up in all red text and once I clicked enter it said "unknown command" and had a HERE button with the "correct" command which still won't work.
Cheats were turned on when world was created-
Thank you for your report!
However, this issue is Invalid.
Your game, launcher or server is modified.
If you can reproduce the issue in a vanilla environment, please recreate the issue.
Any non-standard client/server/launcher build needs to be taken up with the appropriate team, not Mojang.
Any plugin issues need to be addressed to the creator of the plugin or resource pack.
If you have problems on large servers, such as The Hive and Hypixel, please contact them first as they run modified server software.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Customer Support – 📖 Game Wiki