Hey,
I'm using JIRA cloud for Excel and it worked very well.
For time to time I see a change in behavior of the refresh data.
I added calculated fields after the last field, and the refresh worked fine and only updated the relevant columns in the table. Today for some reason (and not for the first time) the refresh button clear all the active sheet and generate a new table. Also, when I had a filter on the table the refresh used to work as well and not stopped with an error "InsertDeleteConflict".
I really like using this plugin but the inconsistency making it really hard to base on.