Users Assigned to Projects/Tasks Do Not Have Access

We have a Fusion scenario that converts requests to projects based on status. Once these requests are converted, we're having issues with users who are either primary contacts on the request and project, or users who are directly assigned tasks not being able to access the project or task.

For example, this user is assigned to this task, but cannot access it. They are a standard user with edit access to tasks, and we have the setting for "when someone is assigned to a task give them manage access to the task". I've checked everywhere I can think of for other access restrictions that may be causing this.