Hi Chris,
You tried installing OMERO.mapr? Did you try to follow the "User-edited Map Annotations" section at https://github.com/ome/omero-mapr#user- ... nnotations ?
That should allow you to search for Values for *any* Key or for configured keys (e.g. LabNotebookID).
See the intro of https://github.com/ome/omero-mapr for a bit more info on how namespaces are used.
We are certainly aware that searching doesn't work very well for Map Annotations.
Regards,
Will.