If you're having a problem transferring a TCX file to your Wahoo device it would probably be best to contact Wahoo for support, as we wouldn't be able to diagnose what the issue is. The file you're downloading hasn't really changed much at our end of things, so should meet TCX file standards.
When I first got my wahoo bolt I could download a tcx route to it straight from plotaroute on my phone to the bolt
For the last few months it now fails to recognise the tcx and won't download. A real nuisance when deciding a route when out and about
DESKTOP TABLET MOBILE
(no app download required)