Unity project won´t open on Windows, runs perfect on iMac

Hey all!

Normally I am working on an iMac and macOS and the project is hosted on a self-hosted instance of Bitbucket. So far so good.

I installed Unity on a headless Windows machine (for performance reasons and outsourcing some intense tasks which will take long and over night :) ) and checked out the project from Bitbucket.

The project is completely in the same state as on my iMac.

The project is available within the Unity Hub, but when I click to open it, Unity splash screen shows up and immediately disappears and I am back at the Unity Hub again.

I checked the logs and found the following:

The upm log says:

[2020-04-11T07:17:03.546Z][INFO] Starting Server

[2020-04-11T07:17:03.554Z][INFO] Server started on port [57688]

[2020-04-11T07:17:03.663Z][INFO] Health Request received

[2020-04-11T07:17:13.557Z][ERROR] [Unity Package Manager (Upm)]

Parent process [1008] was terminated

The editor log says:

[LicensingClient] ERROR Failed to connect to local IPC

[Licensing::Module] Failed to connect to channel: LicenseClient-**

[Licensing::Module] Successfully launched the LicensingClient

[Licensing::Module] Successfully connected to LicensingClient on channel: LicenseClient-**

[Licensing::Module] Successfully launched and connected to LicensingClient

Entitlement-based licensing initiated

[LicensingClient] Licenses Updated successfully in LicensingClient

LICENSE SYSTEM [2020411 9:17:2] Next license update check is after 2020-04-12T07:08:48

Built from '2019.3/staging' branch; Version is '2019.3.9f1 (e6e740a1c473) revision 15132480'; Using compiler version '191627012'

OS: 'Windows 10 (10.0.0) 64bit' Language: 'de' Physical Memory: 16334 MB

[Licensing::Module] License is not active (com.unity.editor.ui). HasEntitlements will fail.

BatchMode: 0, IsHumanControllingUs: 1, StartBugReporterOnCrash: 1, Is64bit: 1, IsPro: 0

No valid Unity Editor license found. Please activate your license.

[Package Manager] Server::Start -- Port 57688 was selected

COMMAND LINE ARGUMENTS:

C:\Program Files\Unity\Hub\Editor\2019.3.9f1\Editor\Unity.exe -projectpath XXXXXX -useHub -hubIPC -cloudEnvironment -production -hubSessionId XXXXXX -accessToken XXXXXX

Exiting without the bug reporter.

Application will terminate with return code 0

Interesting thing is, that it says the license ain´t no valid one. But it is a normal free personal license ... the same way, I am using a license on macOS ... and there the project opens normally.

Do you guys have any idea what is going on and how can I fix this (beside reinstall Unity Hub, wich I already did and did not help :( )

Regards