To reproduce, install the extension, then create an estimate for one work item by clicking on "Add Estimate" and filling out the form. This works fine. Then go to a second work item and click on "Add Estimate". This hangs indefinitely and in the dev tools the following errors appear:
TFS.WebApi.Exception: TF1590005: Document with id [OUR ORG] does not exist in collection Default for Current = tae.6.ba
at g (https://cdn.vsassets.io/bundles/vss-bundle-common-vK43pFpJYH8nmuNnhGRpfahsX3fVlXcLh686oXr7ZGk8=:79:499)
at https://cdn.vsassets.io/bundles/vss-bundle-common-vK43pFpJYH8nmuNnhGRpfahsX3fVlXcLh686oXr7ZGk8=:79:3520
at nt (https://cdn.vsassets.io/bundles/vss-bundle-common-vK43pFpJYH8nmuNnhGRpfahsX3fVlXcLh686oXr7ZGk8=:79:763)
at https://cdn.vsassets.io/bundles/vss-bundle-common-vK43pFpJYH8nmuNnhGRpfahsX3fVlXcLh686oXr7ZGk8=:79:3452
at l (https://cdn.vsassets.io/bundles/vss-bundle-common-vK43pFpJYH8nmuNnhGRpfahsX3fVlXcLh686oXr7ZGk8=:33:8126)
at https://cdn.vsassets.io/bundles/vss-bundle-common-vK43pFpJYH8nmuNnhGRpfahsX3fVlXcLh686oXr7ZGk8=:33:8352
at t.when (https://cdn.vsassets.io/bundles/vss-bundle-common-vK43pFpJYH8nmuNnhGRpfahsX3fVlXcLh686oXr7ZGk8=:33:3784)
at t.u.promiseDispatch (https://cdn.vsassets.io/bundles/vss-bundle-common-vK43pFpJYH8nmuNnhGRpfahsX3fVlXcLh686oXr7ZGk8=:33:2828)
at https://cdn.vsassets.io/bundles/vss-bundle-common-vK43pFpJYH8nmuNnhGRpfahsX3fVlXcLh686oXr7ZGk8=:33:1653
at MessagePort.t (https://cdn.vsassets.io/bundles/vss-bundle-common-vK43pFpJYH8nmuNnhGRpfahsX3fVlXcLh686oXr7ZGk8=:33:5777)
Failed to load resource: the server responded with a status of 401 ()
It seems that this tends to happen if clicking on a work item and then immediately "estimates" without waiting for the time/effort widgets further down to finish loading. If I leave it an extra 10-15secs then this problem seems to disappear.