Power BI Output - Cannot append to dataset

Question

Hi, I can create a dataset using the Power BI output tool, but when I then try to append to the dataset in the options, I get this error

FYI there are no results available if I click on the dropdown beneath Incoming Connection #1:

Does anyone know why I get this error and how to fix it?  Thanks

AdamGSmith · Accepted Answer

To anyone now viewing this post, the issue has resolved itself 3 weeks later without any intervention.  I don't know why.