addDataLoadedListener not firing when add in (extension) placed in workspace tab

Summary

DataLoadedListener firing as expected if BUI add in is in workspace, but not if add in is placed in tab

Content

Below is the code snippet for simple BUI add in which can be used to demonstrate behavior. If placed in (incident) workspace, it works as expected. If placed in tab (in the same workspace), it does not. Is this "behavior by design" or I am missing something? If this is true, is there some workaround? We are doing a lot of integration with external systems via web service calls. We have it working just fine in the console add ins. The idea is to load this data while agent is busy with intro questions, and be ready when needed (and be