Hi
Are your test bets not displayed like in the attached screenshot? If not, please open a new Profile and try it again in the new Profile.
or
If you mean the test bets are not in the Test Statement, then you are either deleting the markets before they have been settled, or you have incorrect Test Mode settings. The best Test Mode setting is to have only this ticked:
Download results from Betfair wherever possible and settle markets automatically
nothing else ticked on that settings screen.