Table sorting in Power BI desktop

Hi, 

Turns out that because I had another table in my data model that was using the same headers as this table, it was causing the conflict. I changed the table headers and it worked fine. 

How I get around the same "null" values is by going into power query editor and then filtering those out, going back to DAX and then set the sort order before going into power query editor and removing the filter. It still keeps the same sort order then. 

I didn't realise Power BI would consider a totally non-linked table to sort the current table but that was my issue and it is now resolved. Unfortunate that it took me almost an entire day to figure this out!