Happened to me last night too. Mixed with a ml of bac, put it in the fridge and it gelled. Added another ml and it gelled more. Planning to do one vial at a time now and keep it out, using 2mg daily for five days then two off.
I'm seeing conflicting answers on how to store Tesamorelin once it's mixed. Thought fridge storage for up to a week at 4-8 degrees was fine, but the approved paper says room temperature in a dark place. Wondering if that's causing the gelling in vials after fridge time. Saw a post explaining the issue because this one has a longer amino acid chain than most other peptides people use.