Field above a hidden Top/Bottom filtering context field can not be a custom group field. You are trying to remove field '|0', ...

Field above a hidden Top/Bottom filtering context field can not be a custom group field. You are trying to remove field '|0', which will leave a custom group field, '|1', above a hidden Top/Bottom filtering context field, '|2'. Please make sure field '|2' is on the Axis or you can remove field '|1'.