For the Timelog extension to work as expected all Customers needs to have a Contact Card releated to the customers.
You can see your Contacts in the solutions if you Search for Contacts.
Each time you create a new Customer it will automatically create a new Contact Card for the Customer.
If you have converted data you might miss the contact cards.
What if the Contact Cards are missing?
You can create all missing cards if you follow the steps above:
1. Go To Business Central
2. Search Create Contacts from Customers
3. Run the job
4. There will now be Contacts on all Customers in the system