I’m also having the same issue on the same device. It worked fine the first time it was powered up after install, but since then CarPlay fails to work.
The device shows as connected to the iPhone, but doesn’t ever fully connect - you received the “Connecting to the device…” prompt, then it eventually times out and states “Unable to connect to apple CarPlay”.
I’ve tried multiple iPhones, all running different iOS. Versions, and all seem to suffer the same issue.
Having a look online, it seems that we’re not the only people with the issue. A few people in Europe are also reporting the same problem.
I’ve also called/emailed Alpine to try and get assistance from their side. As it stands,
this expensive head unit isn’t fit for its primary purpose.