this is the simplified model of your circuit. I used other diodes but this doesn’t affect the result.
As well as the mosfet M1 approximates the behavior of an ideal switch there is no
reason because the period of L1 current and charging voltage period of capacitor are mismatched.If Ton=4us and Toff=58, they must be equal to about 60us.If L1 current period is 30u and charging voltage period is 26us is ok, but Ton=4us and Toff must be 26u.Try replacing M1 with a new one, or with another switching mosfet.
