Randy has gone through things on this end with a fine tooth comb. He has checked all the settings. He has looked at what Tapatalk is allowed to do. He hasn't found any problems.
At best all we can come up with is some setting on your phone is messed up and you don't know it - or you have picked up a bad cookie someplace and it is interfering with your ability to post.
So it's only the "Show your Finished beads" category giving you this problem?
Since I don't use Tapatalk, I'm going to have to ask other Tapatalk users to attempt posting to that particular forum and let me know if they have the same problem. If other people cannot post with Tapatalk then we might be able to use that information to help track down the problem. Right now you are the only one having Tapatalk problems, and the error you are getting has left all of us in the Administration scratching our heads. This is why we think it might be something to do with a setting on your phone.