Missing modules in Umbraco 16

[StephenPedder]

Hi.
I have used the SeoToolkit library in an Umbraco 16 application with no problems. I have tried to implement it on another site but when I go to the SeoToolkit tab in the Umbraco backoffice, the page displays but none of the modules (eg. meta data, robots.txt etc) display. There aren't any errors in the console and I can't see anything in the Umbraco log files.

Is this a known issue and is there anything I can try to get this working?

Thanks.