Hi @Marcel (work) ,
Thank you for posting your issue to Microsoft Q&A forum.
According to below Tech-Share threads, if you are using high DPI Screen, you can set the displays at the full resolution with 200% scaling. Please kindly check if it works for you.
https://social.technet.microsoft.com/Forums/lync/en-US/2c4f1b5b-f95b-4e0f-923e-68ff608691ce/small-or-missing-mouse-pointer-in-rdp-session-solved
In addition, mouse cursor pointers settings are stored in user profiles, so you can switch users to login RDP and check if the issue occurs on all users or specific user.
If it only occurs on specific user, you can delete the problematic user profile and reconnect to the remote session to create a new user profile.
Hope the above information help you.
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