Same issue here! The Trail map sections are either loading veeeery slow, or not loading at all. Some may be loading, but I need them all to load, to see where I am, am going or whatever.
This issue is so persistent that, like others, I also revert to the "Street" Apple Maps. I've never had any issues with those, but less detailed.... Therefor this must be fixed, since it's a Premium feature anyway. Current phone is iPhone Xr, but previous iPhone 8 had the same issue. Another iPhone SE2020 we have also experiences the same issue. We all have subscriptions with a premium provider. 4G all over the country.
.png)