Best practice for loading Routes

I’m having an issue with loading routes that I’ve created in either PlotARoute.com or Strava. Both methods seem to be stuck on ‘calculating’ on the watch when loading the route.

Plotaroute.com routes have been exported as a .FIT file and placed in the NewFiles folder of the watch, on the PC.

Strava routes have been imported to the watch through the routecourse app / https://dynamic.watch/ method.

This happens when it’s set to ‘Use Map’ so is this calculating problem occurring from it working out Turn-by-Turn notifications? When I change it to ‘follow course’ it doesn’t have any calculating to do, but then I’m guessing I’ll get no TBT?

Is there a better method to creating a route, loading it with TBT and minimal calculating time?

Thanks!

(just realised I've posted this in the wrong forum but might still be relevant, can be deleted if need be)