You can only preview text ads derived from the first 5 rows of your Keywords & Data CSV and Stem Keywords list in Step 4 Ads screen.
To keep Keyword Machine running smoothly in your web browser, we only load a subset of your data into the ad preview. You should get a good understanding of your text ads, along with how your Backup Ad kicks in using the first 5 rows of your imported CSV.
Please note that 5 rows from CSV does not necessarily equal first 5 text ads previewed. The number of text ads previewed depends on your Keyword Batch settings, how you’ve grouped campaigns/adgroups, tokens used in your ad template and the number of ad templates created.