Dear Alexander, I apologize, I misunderstood what I was seeing. It appears that tab indeed works just fine but only when doc extension is present (such as .html or .php). I had created a new document without extension and emmet did not work with tab. That does not seem to be a problem at all.
I used to be able to expand Emmet with tab in Textastic, but can no longer do that. I must use CTRL + E. I’m using iPad Pro 2nd gen, running most current iOS and using Apple smart keyboard....so there is no option of keybinding. I assume this is a bug since I used to be able to expand with tab not very long ago...a few weeks?
Customer support service by UserEcho