Your door to floor gap should not exceed 10mm. If it does, you may find that the door can become ‘stuck’ on the pin. This is an easy fix. You will need to purchase a Fantom 5mm packer here. Note: you can use more than one 5mm packer if your gaps require you to do so.
Is you floor sleeve siliconed into the floor? Also check that it is installed straight. If the pin is not glued in or installed straight, you may find the door is sticking.
If you have a steel pin and a stainless steel striker plate, you will need an over-mould pin if you find your door is sticking.
These can be found here. You may also have metal filings stuck to the face of your striker plate. You will need to remove your door and check this.