The problem of acronyms usage with RIVA and WFST decoder

Hello, everyone. I am trying to add support for acronyms to RIVA pipeline with WFST decoder. I add acronyms to the arpa file (all letters in upper case). Everything works correctly with the nemo model.

However, when I work with the RIVA model, this approach does not work.

Does anyone know what the reason might be?