Wordfence security plugin is causing errors with saving WBS rules

Hello, this might be useful to someone.
After filling table with new fedex prices, in WBS rules, I was not able to save them. After clicking on save, error occurred, some red tab in bottom right corner. Usual method is disabling plugins one by one to see what cause that error, once, when wordfence was turned off, I was able to save data. Cheers, I hope this will help someone.