Using LibreOffice as a file Viewer for another program. Trying to view an RTF file, but it default converts it to TXT. How do I set it to view RTF as RTF not TXT?

I am using SIRSI Workflows at my library for automation. It allows me to print labels. It sends the file to an office program of my choosing. I chose LibreOffice. I selected swriter.exe as the program for viewing. It automatically opens the program and opens the file being viewed. The problem comes when it is recognizing the file as a TXT file while it is actually an RTF file. I have had others open it on their MSOffice computers, and the file opens as RTF. I have had them send me the file that comes from SIRSI and it emails as an RTF. I can open an RTF file in LibreOffice if it already exists as an RTF file. But, the program I am using requires the office program to recognize it is an RTF in order to view it.