http://i.imgur.com/R5eBOIA.jpg(Bottom middle of the screen, the error with a random ent.)
https://github.com/wiremod/advdupe2 I would recommend downloading the latest version, which has less bugs and more features.
Or don't.
Anyways, open up the advdupe2-master file.
go to advdupe2-master>lua>advdupe2 and then open the file called sv_clipboard.lua
I do not know the exact fix, but I have a vague idea from when I helped a buddy solve the problem. Basically, search "IsAllowed" and there should be 6 results all under the same string. From what my buddy told me, he said all he had to do was change the "false" statements to "true", and it solved the restricting of SENTs.
This is supposed to be at the top of the post, but for some reason the font messed up. Basically what I said was, anyone below Admin is plagued with this issue. That issue being all SENTs are restricted. Rendstung also reported this issue before.