The PAM RDP client has limited support of clipboard formats. We document this on page Known Issues:
RDP Client Does Not Support Custom Clipboard Formats (DE334815)
The RDP Client supports only the following standard clipboard formats for copy and paste operations:
The RDP Client therefore does not support applications that use custom clipboard formats to handle data that cannot be translated into a standard clipboard format. Performing a cut and paste operation in such an application via the RDP client can result in data loss.