In the early version of FOEX i.e. v1.x we automatically added a Reset button to the form which did not require you defining one in the builder. We later introduced functionality in the FDA to automatically create this button so that you could add conditions/authorizations and translate the label. For backwards support we still add this button automatically if we can't find a button assigned to the form with the button name RESET (the default name used by the FDA).
If you have created a custom reset button manually on the form can you ensure the button name = RESET