There is a sealant called Fugit that does not have Latex or Amonia in it. Problem is, as you say, you struggle to get the tyre to seal or attach to the rim bead. What I do is to rub some of the Latex based sealant on the tyre bead and it works fine. The Latex or Amoniac causes bubbles to form on the tyre. Had to throw away many tyres due to this.