Upfront Not Saving Changes

Hi guys!

I'm having an issue which is common based on my research but I have yet to find a reliable solution.

I am using Upfront and have been having trouble saving changes. There is always an error which says "Unable to save theme color style". I've tried some solutions on the forum such as changing mod_security but it still doesn't work. And I believe it does compromise some security issues. I tried switching themes from Fixer to Spirit too and the issue remains the same.

I have no other plugins installed except for the WPMU Dashboard and have changed permalinks to the post permalinks.

It occasionally saves about 10% of the time but most of the time it doesn't save. Any ideas guys?

Thanks for your time!