Being unable to edit the quotation tab in client data will happen if you are selected on the client list but not the sales advice tab (on the left side).
This is an example of the problem that a user may run into when trying to edit the quotation tab (despite being in edit mode).
Solution:
The easiest way to overcome this issue is to:
- Select the Sales Advice tab (after selecting the client),
- Then select the sales advice item from the list
- Select edit on the bottom right
- The quotation tab will now be available
After following steps you should now be able to successfully edit the quotation tab!