TIL => you need files in your repo when tying to pipelines
When you’re tying pipelines to a repo, you’ll notice only repos that have files in them are available. This is because Azure DevOps needs to be able to access the files in the repo to create the pipeline. If your repo is empty, it won’t show up as an option when you’re trying to tie it to a pipeline.
…and that’s all. …so next time if you’re quickly setting up a repo and then a pipeline to tie to it but it’s not showing up, just add a file to the repo and it should show up in the list of available repos.