What I would like to suggest is first extendyour result set using customDimension. Then you will need to cast the new column to a string, integer or double. The reason for this is what customDimensionsis considered a dynamic column
Quick example:
traces
| extend sortKey = toint(customDimensions.MyCustomProperty)
| order by sortKey asc
Casting Options:
- to string()
- toint ()
- double ()
, project-away .