You can have the following case:
It happens because you have done a manual numbering, and the report is sorted by Root and Number fields. Double click on the symbol in order to check its properties:
To obtain an alphabetical order you have to set Automatic Mode and force component Mark using Root and Number fields. You can type in the fields or use the buttons on the right:
After that you have to set Manual Mode in order to avoid unwanted changes when renumbering:
This is the result:
Using this method you can get an alphabetical order in your elecworks BOM.
Note: elecworks version used 2016 SP3