Power BI Unable to select sort columns

If a sort has already been specified, it will be greyed out.

1. Click on the Data icon in the upper left.
2. Click on the column that may have a sort on it.
3. Click Clear Sort.
4. Click on another column, then click back to the column you want to sort.
5. Sort By Column will no longer be greyed out.

When you create Report using Power bi data set (not connect directly to database) you cant use column sort it will appear disabled

The preferred way to do this is to use a sort by column that looks like this:

Month | MonthSort
Jan   |         1
Feb   |         2
Mar   |         3
Apr   |         4
May   |         5
Jun   |         6
Jul   |         7
Aug   |         8
Sep   |         9
Oct   |        10
Nov   |        11
Dec   |        12

Then on the modeling tab, select the Month column. Then click the Sort By Column button in the ribbon and select MonthSort.

https://docs.microsoft.com/en-us/power-bi/desktop-sort-by-column#sort-using-the-sort-by-column-button

This is an old post, however, I was not able to solve based on above answers. So updating based on what helped me.

In Power query editor, create a new column in the same table as month number for corresponding month. Apply the changes and return to report screen.

In report screen, select the field "Month", go to modelling and click sort by "Month Number". Note:- this makes Month to be sorted based on Month number rather than alphabetical.