Sorry for that. Sometimes user think other plugin permission, so as a measure i told you to check that.
Any role user can access that or all users getting that error?
Do you use any custom code for this plugin?
This error means any plugin/code is using hook fep_current_user_can to dynamically change access permission. Can you deactivate all other plugins and change theme to one of default theme then test? Then activate one by one. if you found any conflict let me know so that i can try to solve the issue.
Are you using any caching plugin? If yes please clear cache and exclude message page from caching. Also deactivate caching plugin temporarily.
If still not working then it needs some debug from php. If you are comfortable to change php then i can live chat with you and give you debug code. Otherwise you can give me access permission to your website so that i can debug in your website.
array _shift will remove first element from array. So it remove your role.
This does not only affect this plugin but other functions as well. Your website is a membership website. Your member will not be able to access content as their roles is removed.
I have corrected that. I hope this will solve your issue.