The General affiliate link is not displayed

This can be caused by two main reasons:
First one is your tracking settings - if you are using "Standard links (Redirect links)" OR "DirectLink style (no URL parameters)" linking method, then the general affiliate link would not work anyways, so the system turns it off automatically.

Second reason can be your template code - if you have modified it, there can be a problem. Try to change to default theme and you will see if there is any change. If so, check the original code and replace the modified one with the original one.