Leverkusen are in no mood to entertain such ideas, however, as Boldt maintains they have no desire to let him go and pointed out that it is the German club who hold the power when it comes to negotiations.
"Well now the time starts again when there is some insane [transfer] talk," he told Kicker.
"There is no offer for Leon. We have absolutely no thought of selling him. He has a contract until 2022 - and we are on the driver's seat."
Having moved from Belgium halfway through last season, Bailey struggled to make an impact in the early months of his time at the BayArena, but Boldt is happy to see such a quick improvement.
"His start at Leverkusen was not easy, he was still impressed with the hype that was being made about him in Belgium and made some mistakes," he added.
"Today we see a boy who has learned from his behavior and is fully integrated into the team."