I used to suffer from the same issue on selected rapid chargers, primarily Instavolt and Ionity. As soon as charging started, it would stop. The charger would indicate the car was stopping the charge.
Once you have a failed charge, getting it going again can be a pain and frequent attempts causes the HV battery to disconnect. Only a power off and wait for 5 mins resolves this.
To avoid the issue in the first place:
1) Turn off the car.
2) Connect the charger.
3) Lock the car (or on FL models, you can tap 'Lock' on the central display if you intend on waiting in your car whilst charging). You'll hear the charging port on the car lock the cable in place.
4) Start charging*
Once charging, you can unlock the car to get back in again. Note that charging will pause when the car is unlocked, and will not resume until you re lock it.
* If you are at a charger that requires you to tap your payment card before the charger will release, lock the car via the fob as soon as you plug it in. If the charger attempts to start charging whilst the port is unlocked, charging may fail.
I've had a 100% success rate on all rapid chargers since following this process.