i have also faced this issue. its not a js error or anything. if you have saved your login credentials in your browser means, its automatically storing in paypal cofig. i just removed the configs. its working
Please see Renon's answer above.
To further elaborate on the issue, you can search your database for other affected rules. First, get the current staging version for your site:
SELECT * FROM `flag` WHERE `flag_code` = 'staging';
You will see something like this:
Next, take that timestamp, and inject it ...