Thank you for reporting!

For issues:

• If the issue seems to affect only one mod, report to them instead of here.
• Remove NEI and FEI to see if they are causing the issue before reporting.
• If you crashed, please paste the crash log to gist and link it here.

For suggestions:

• Please do not suggest features from NEI. See this spreadsheet before requesting.

Seems that JEI's cheat mode doesn't stay when reloading the world. Any idea why this is, despite cheats being enabled in the world's settings?

Thanks for the report!
This has been fixed in the latest versions of JEI.