In the Scan class editor, all scan classes are sorted alphabetically.
But in Tag editor dropdown for choosing Scan Class they are shown unsorted in some weird order and it’s very difficult to find the right scan class if you have many of them.
Where are this scan classes stored?
The scan classes are stores in the SQLTSCANCLASS table, which is updated whenever any changes to scan classes happen. My guess is the editor retrieves and sorts on the NAME column, whereas the scan class selector for a tag is sorted by the SQLTSCANCLASS_ID column.
Where is that SQLTSCANCLASS table? How can I see it?
OK, I found it in internal DB in the Ignition gateway.
But there is no logic in this…
When you export the scan classes in CSV file, they are sorted by NAME.
So I exported all scan classes, delete all scan classes from Scan Class editor, save, import back from CSV and it’s the same…
When you look at the internal DB (select * from SQLTSCANCLASS), you can see the ID column and NAME column are OK, but in the dropdown, in the Tag Editor, it’s still everything messed up…
Did you restart the server after importing the scan classes? Changes to the internal database that do not go through the ORM need a service restart to take effect.
Yup, I restarted Ignition, restarted server (VM), cleared the cache (.ignition folder), … nothing helps… 
(Realtime) scan classes will be sorted to match the scan class editing window in 7.9.8; see: http://ideas.inductiveautomation.com/forums/255378-ignition-features-and-ideas/suggestions/32166658-sort-scan-classes-in-the-tag-edit-create-window
