Missing Edge experimental runs

https://wpt.fyi/runs?label=master&label=experimental shows few runs in the past week.

If we look at https://dev.azure.com/web-platform-tests/wpt/_build?definitionId=1&_a=summary&repositoryFilter=1&branchFilter=9077%2C9077%2C9077, we almost always have at least one job taking more than 180 minutes. Need investigation as to why that's happening.

cc @mustjab 