So far, I noticed that it may depend on the settings for geographic region and language.
Anyhow, it is intermittent in some cases while persistent in other.
Finally, for the most of the terms that we do research on, we do have TM allowance from the owner to use it in ad text.
I believe that this should be enough (the allowance) to turn the switch ON for keyword tool as well. Let the owner manage it.