I have this issue for a couple of days now figuring out what is the problem causing it. I have a protected posts that requires level 1 access. When i click on a protected posts it redirects into the membership page but its blank. But when i click on the protected post category the content of the membership page is there.
I tried to deactivate all plugins but still no luck thinking it might be a plugin conflict issue.
By “blank” I guess you mean absolutely nothing on the page. In that case you’re probably getting an error, and I’d suspect Mod Security.
Please see this article:https://s2member.com/kb-article/mod-security-odd-403-503-500-errors/
I hope that helps! 
Yes. nothing on the page. Only the blue background of the page. Ok i’ll try checking that.
But if you could able to visit this protected post - https://myfishingcapecod.com/extended-big-bass/?hilite='extend'%2C'bass' and see the issue.
I see.
So it’s not a fully blank page, because there is source code for the page, but it doesn’t finish loading. And it happens if the string is too long, I tried removing part of the variables and then the page loads fine.
I would take a look at Mod Security, as the article describes. You may need to contact your web host. See if the errors log mentions something.