A unique subset of settings can cause a situation where nobody is able to approve a resource's time cards. This occurs under the following conditions:

• There is only one approver for a time card
• That approver is the same person who submitted the time card
• That approver is not allowed to approve their own time cards

 Edit the time approver's resource profile and allow them to approve their own time. This setting is time-phased. So you might need to go to the history row and enable it for historical time cards.

 Have an administrator with the cost center permission Administer Time Workflow force the card to approved.

Go to your project and change the time approval configuration to allow more approvers. For example, change it to PM Team.