Legacy module not working correctly after migration from 7.14 to 8.6

I’ve got a custom module and the listview is not working quite correctly.

The module has a relation to the Users module and the field should show a link to the users module but the column remains empty. The details and edit view are correct. Also in the logs I see the follwing error:

Fri May 31 10:24:17 2024 [28608][617d6a52-fddc-1eda-a4c4-57533ac8e921][WARN] ModuleNameMapper | mapName | ‘assets_Assets’ not mapped to ‘frontend’
Fri May 31 10:24:17 2024 [28608][617d6a52-fddc-1eda-a4c4-57533ac8e921][WARN] ModuleNameMapper | toLegacy | ‘assets_Assets’ not mapped

assets_Assets is my legacy module (built with module builder in 7.12).

Cheers,

Tom