Occasionally a corruption or other issue might occur with the user Application.settings file that could result in Reflection Workspace failing to launch.

A quick test and possible resolution could be to rename the file to something like Application.settings.bak, and launch Reflection Workspace again, in which case Reflection Workspace would automatically create a new Application.settings file.

There is more information about this in the following knowledge article:

Reflection terminates after the splash screen is displayed