ThermalLabel SDK generates native printer commands (a.k.a. RAW printer commands) and it might not work in Remote Desktop scenarios because a limitation in the printing technology from MS (called Terminal Services Easy Print or TS Easy Print) shipped with Windows Vista or later versions. MS provides a fix to this issue in the article WritePrinter() with RAW data fails to print with TS Easy Print
Applying the fix stated in that MS article should allow you to get ThermalLabel SDK to successfully print in Remote Desktop sessions.
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