Modifier on Star Item

Hello All

There is one scenario , where a RMA is created against the original order and the return item is the star item , while returning we want to use Manual MOdifier to update the price on it.

We created a Manual discount modifier, however when we try to apply the modifier it gives this message "APP-ONT-250274: No Manual Discount Available"

HOwever, when we try to apply the same modifier to a normal line (non star item) , it gets applied without any issue.

Could anyone help wht cld be the issue?

Thanks

Jy