This is actually an old thread started about 5 months ago. As I mentioned then, I had tried different brushes, mix ratios, always let my bead settle etc, etc. When I pointed it out to my educator she had a go and got the same result as did a few others in the class.
I do still suffer from bubbles, mainly in clear, but not as heavily as in the initial pics. Have just discussed this today with my educator actually, as she has came across it a few times since I pointed it out. She has done some investigating and is still chasing and following it up.
On a clear tip as in the pic, they stand out a mile, in the real world on clients they are very difficult to pick up and no one but myself has ever pointed them out. They have also never led to any kind of service breakdown.