Is the assets config file numeral a higher trainz-build than your trainz version ?
If it is higher a trainz-build numeral it will not show up until you edit the numeral to be your trainz-build numeral. A lesser trainz-build numeral needs not to be edited
Trainz will still not recognize the edited numeral, until you delete 2 files (what ever they may be in TS10), and let the TAD rebuild, undisturbed for @ 20 min, or longer
To find your trainz-build version, build a "New Route" and examine its config file trainz-build numeral
Please wait for confirmation on this by more educated users: Are these 2 files assets.bku, and assets.tdx ?