In the the below the person was asking whether there are many ghosts/spirits at the place (in this case the theme park)
「霊は?多いかな?多くても、しつこくなければまだいいんだけど」
「それはわからない、かな……。」
霊の多寡に言及しているレポートは、さすがにどこを探してもない
The sentence in question has her questioning whether there are many ghosts/spirits, and then she says even if there are many, as long as ..... then that is not as bad / is better.
However the meaning of しつこい in this context isn't clear to me. I am generally familiar with しつこい when used in the sense of "persistant" but I'm not quite sure how to understand it in this context.