Manuel7 said..
Yes back slaps and top of the sail hitting the water means lack of height (for the style of loop), pop over back foot with weight back (hurts forward speed), and possibly sheeting in too early (mast not enough into the wind or forward enough). Possible also board too much into the wind.
Good tips, session three was similar to the second so I think I'm doing all those things not quite right to some extent. Last session wasn't that windy and I was struggling to find ramps and keep speed up. Looking forward to some stronger wind to try some more