I’m sorry to hear you are experiencing this issue. There is a known problem with several languages with Windows 10, including Tigrinya, for which Microsoft are releasing a patch. However, I am not sure if you’d have the patch on your system yet.
Keyman should normally detect when you are installing a keyboard with one of the languages Windows is haveing trouble with, but that clearly hasn’t happened on your system.
To work around the issue, you can associate your Keyman Tigrinya keyboard with Ge’ez instead of with Tigrinya; Ge’ez does not have the same problems on Windows 10. Follow the instructions at Many Amharic keyboards not working (where those instructions say ‘Amharic’, read ‘Tigrinya’ instead!)
More background is available at https://blog.keyman.com/2018/11/keyman-windows-10-1803-and-amharic-tigrinya-sinhala/
I hope this helps!