I'm not sure if this has already been reported as a bug, but it appears as though the WMX Job LOI's do not appear in the Job LOI tab/area in ArcGIS Pro if your job query includes extended properties. I believe another user is having a similar issue (workflow-manager-aoi-not-showing-in-arcgis-pro). Is there a work around for this that doesn't include simply not having extended properties in the query?
I also experience this problem.
Any job query that contains extended properties will not display in the results query map in ArcGIS Pro. However within the Workflow Manger (classic) application the same job query will work perfectly fine showing all the records/jobs in the results query map.