Hey @Ale67, 
Thanks for your posts! While researching I found that our engineers are aware of the heatmap issue. They are working to resolve it as quickly as possible, although I do not currently have an estimated time for resolution.

We will update this post once we have an update. Thank you for your patience. 

Has this been resolved?  I have the paid version and can no longer see heat maps when offline. Thanks. 

Dear Bryant, last friday I went for a ride and I'm sorry to say the situation was even worse: 

not only the heatmap disappeared, but the whole map desappeared, leaving me with a black screen with a blue dot, not moving from the starting point. However the app works in background because you can see the milage and time moving. Indeed, when I finished my ride, I saved it and the tracking and stats were perfect. The problem is that if you cannot see the map this app is useless if you go on new trails.

I was thinking to go for the paid version to solve this problem but I see that there are people having the same problem with the paid version as well. 

Thank you for helping us. Alessandro