BarsOtto said

All these sites do not display these special checks, the settings are okay - there is nothing

That is something sites uses and FF can't change or remove them. If your not seeing them then you got adblocker or Firewall causing it not to work to block your access.

Make sure you are not blocking content.

Start Firefox in Safe Mode {web link} by holding down the <Shift> (Mac=Options) key, and then starting Firefox.

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?