Not able to apply hold at order line level

Summary:

We are seeing that for some of the orders, the Apply Hold button is disabled at the line level.

Content (please ensure you mask any confidential information):

We are seeing that for some of our orders, the Apply Hold button is disabled at the line level.

If we try to apply line level hold using SOAP service we get the error

"Order management can't process your request to apply a hold on the order line for this order. You can apply the hold on the order or the fulfillment line"
Would you know why it prevents the hold at line level, while allowing header level or fulfillment line level hold?