In Discover 2016 or later, when I open my drillhole project and go to edit the data in a browser, I cannot edit it.
Solution
As MapInfo and TAB files are 2D only, Discover needs to import and convert these into a suitable 3D database format in the background when opening/creating a Drillhole project.
This is due to the Drillhole project now opens the 3D cache database, which is a geopackage tables. You will notice if you hover over the tables in the explorer, the tooltip will indicate they are stored in -
C:\Users\USERNAME\AppData\Roaming\Encom\Discover\PROJECTNAME
MapInfo only supports a geopackage being opened in a read only state.
To Edit these, open the drillhole project, then select the DRILLHOLES>Edit Data tool. Note this dialog cannot be closed whilst you are editing you original tables in MapInfo.
Once finished editing, simply click Done and it will save, refresh, validate, desurvey and validate your drillhole database and reopen the geopackage tab file.