Cant add more elements (seem to disappear when i save)

When i add too much elements, the elements won't save anymore.
First i thought it had to do with the max_input_vars in PHP.ini, but i changed that from 1000 to 3000, but that didn't solve anything.

This is what happens:
1) When i add an element, it is added, but when i save it's gone.
2) That lesson is set to concept instead of published
3) The _posts table got 2 new rows, both on the status auto_draft
4) No _postmeta rules are added

I made a video of what happens (i can't grand access at this time because it's a live site). Can i send that to you guys?