Excel Sorting Issue

We have an excel file with a column that has our project numbers with both numbers, and some with letters. We have them all saved as "text", so when filtered and sorted from a -z, they look like this: 400, 400.A, 400.B, 401, 401.A, 401.B, 402.A, 402.B, 402.C, 403... and so on. There has been no problem sorting them properly up until our IT guy updated my excel. Now, it sorts as if I don't have the data as text, so 400, 401, 402, 403 and then 400.A, 400.B, 401.B, 401.B, and so on. Funny thing is that in the drop down menu that pops up when I click on the filter button in the top row, the project numbers are sorted properly there (where you can check and uncheck all the options).    Is there a setting somewhere that I can check within MY excel, because the worksheet itself works fine on other people's computers in my office.  I have Microsoft Office Professional Plus 2016.