Table Multiselect always show Mandatory

We are using the Frappe Version v15.43.0 (version-15)
In our Form, we have a TableMultiselect Field and we marked that as mandatory, If we select multiple values and click save it shows a Missing Fields error as shown in the attached image how do we fix these?
image

Remove the mandatory from the TableMultiselect and check whether the data stays or not.