Unfortunately….With a loop, you will experience the same thing every time you pull & launch the boat.
All factors that I mentioned above must be adhered to for self priming.
I'm sure there is got to be a way to cut (slit) the hose loose from the fitting & get rid of the loop/s.
There needs to be a constant uphill from thru-hull , to strainer, to pump, to unit…And all this (except unit) needs to be below the waterline or you will have trouble everytime you haul & launch…Also many times after being underway.
Steve~