The opposite of the compulsive planner is the smoozer, a project manager who views their role has only talking with the client or working on the project team’s morale. For them creating a plan is a chore; working issues a drag; scope management a theoretical concept. With this type you have excellent customer satisfaction, for a while anyway, but you have no idea where the project’s going.
Usually moving this type of project manager is difficult, at least until the project goes pear shaped. What you do depends on the context in which you find yourself.
If they are on a project whose output is critical to your project then you have to demand regular detailed status reports and advise the client of the risks if the other project is late.
If they report to you then you can either force compliance with your project management system or, if the budget allows, you can support them with a good planner.
If you work for them then recognize that you are going to have to step into the breach and the team is going to have to run the management system.