The Custom Role has Full permission on the sales transaction like Estimate or Sales Order but under Items tab, the Cost Estimate Type and Est. Extended Cost are not editable and showing in Inline Text.
1. Navigate to Setup > Users/Roles > Manages Roles.
2. Edit the role in question.
3. On Permissions tab > Transactions subtab > add "Override Estimated Cost on Transactions".
4. Then set the Level to Full.
5. Click Save button.