To create bins from a dimension calculated field in Tableau is different to creating bins from a non-calculated field dimenion. With a dimension calucalated field the bins also have to be created in a calculated field. The initial calculated field CAN’T CONTAIN AGGREGATION (sum, count, etc) otherwise the calculated field defining the bins will be a Measure when it needs to be a Dimension. If it’s necessary to create bins from a calculation, which will be a measure field, there’s a post on how to do this at this link.
To create the bins an IF…THEN…ELSEIF…THEN…ELSE…END function can be employed.
IF CalculatedField < 10 THEN “10”
ELSEIF CalculatedField < 20 THEN “20”
ELSEIF CalculatedField < 30 THEN “30”