Changing the client in a Smart Project using a Groovy macro only seems to work partially

When using the setCustomerInternal method to change the client in a Smart Project, it only seems to work partially. The new client is shown in project views and also when using the getCustomer method, yet there is one part of the project where it still shows the old client from before the change:

This makes me wonder if we are doing something wrong or are forgetting something. The same issue occurs when changing the client reference number using the setCustomerProjectNumber method.

In addition, after changing the client, we are presented with the following error when trying to update the client notes field you can see in the screenshot above:

Does anyone have any ideas about how to solve this issue? We would like to be able to change the client for existing Smart Projects using a Groovy Macro, because the XTRF UI does not offer this option.