We have the same problem with 6.9.1. I solved it by starting the first time with MultiTenancy enabled, then I disabled it.
Also see this:
https://support.aspnetzero.com/QA/Questions/6778
If I set MultiTenancyEnabled = true on the first run this does not happen.
If you are using VS 2017 the problem is this:
https://stackoverflow.com/a/55529011/1223919
SDK 2.2.2xx is only supported in VS 2019. For VS 2017 you need SDK 2.2.1xx.