Can't build hello world app on real Apple Watch

Hi,

I'm trying to buil a WatchKit App on my new Apple Watch 5 with WatchOS 6.1 from Xcode Beta 11.3 (same problem also with non-beta Xcode 11.2), but I can't install the app on the real device.

The simulator works just fine, but when I try to run it on the device it tells me that it can't install the app with this advanced details of the problem:

Details

Unable to install "Prova Watch WatchKit App"
Domain: com.apple.dtdevicekit
Code: -402620395
--
App installation failed
Domain: com.apple.dtdevicekit
Code: -402620395
Failure Reason: A valid provisioning profile for this executable was not found.
User Info: {
    DVTRadarComponentKey = 487927;
    "com.apple.dtdevicekit.stacktrace" = (
  0   DTDeviceKitBase                     0x00000001210186e7 DTDKCreateNSError + 109
  1   DTDeviceKitBase                     0x0000000121018de9 DTDK_AMDErrorToNSError + 792
  2   DTDeviceKitBase                     0x000000012105856a __90-[DTDKMobileDeviceToken installApplicationBundleAtPath:withOptions:andError:withCallback:]_block_invoke + 164
  3   DVTFoundation                       0x0000000107711c22 DVTInvokeWithStrongOwnership + 73
  4   DTDeviceKitBase                     0x0000000121058301 -[DTDKMobileDeviceToken installApplicationBundleAtPath:withOptions:andError:withCallback:] + 1589
  5   IDEiOSSupportCore                   0x0000000120ee0a25 __118-[DVTiOSDevice(DVTiPhoneApplicationInstallation) processAppInstallSet:appUninstallSet:installOptions:completionBlock:]_block_invoke.352 + 4523
  6   DVTFoundation                       0x0000000107842e8a __DVT_CALLING_CLIENT_BLOCK__ + 7
  7   DVTFoundation                       0x0000000107844562 __DVTDispatchAsync_block_invoke + 809
  8   libdispatch.dylib                   0x00007fff67df6553 _dispatch_call_block_and_release + 12
  9   libdispatch.dylib                   0x00007fff67df74de _dispatch_client_callout + 8
  10  libdispatch.dylib                   0x00007fff67dfca9e _dispatch_lane_serial_drain + 597
  11  libdispatch.dylib                   0x00007fff67dfd422 _dispatch_lane_invoke + 363
  12  libdispatch.dylib                   0x00007fff67e06aa1 _dispatch_workloop_worker_thread + 598
  13  libsystem_pthread.dylib             0x00007fff68050763 _pthread_wqthread + 290
  14  libsystem_pthread.dylib             0x00007fff680505c3 start_wqthread + 15
);
}
--

I tried both a stand alone WatchKit App and a Watch+Phone app.

With the Watch+Phone app I can install it on my phone just fine, but then I still can't run the watchkit app target on my watch.

I'm using my personal AppleID account (not a paid one, not sure if that's needed to just test an app on my watch).

In the signing and capabilities I checked "Automatically manage signing" and my AppleId as team.